Instead of inserting the hook into the top of the indicated stitch (the 2 strands that look a bit like a chain), you put the hook round the post of the previous row. If you think of the previous row stitch as a capital T, you work round the vertical column rather than into the cross bar.http://www.dummies.com/crafts/crocheting/stitches/how-to-work-front-post-double-crochet-stitches/
It means alternate between front post double crochet and back post double crochet.
The word "post" in crochet is referring to the whole stitch--generally a "tall" stitch (such as a double crochet, triple crochet, etc).The reason the instructions refer to the stitch in the row below, is so the crocheter understands that you are to stitch around the stitch below--the "post" of the stitch. Otherwise, if the instructions stated that you were to double crochet the next stitch, you would understand that you would be double crocheting into the top of the stitch below, versus crochet around the length of the stitch.You also notice that the instructions will say to "back post double crochet (bpdc)" which means to bring your stitch around the post from the back position. So, "front post, double crochet (fp dc)" would mean to bring your stitch in from the front side of your work.
for back post single crochet - insert hook from back to front around post of next stitch, yarn over and pull up a loop even with last stitch worked and complete single crochet for front post single crochet - insert hook from front to back around post of next stitch, yarn over and pull up a loop even with last stitch worked, and complete single crochet This is easier explained in photographs or video.
At the stitch you want to have a front post, you do a normal double crochet, except you drop down to the 2nd row down to insert your hook. When you pull it through, hold your yarn loosely in your left hand and gently pull it up to the level of the row you are currently working on.
The front stitch, often referred to as the "front post double crochet," is a crochet technique where the stitch is worked around the post of a stitch from the previous row rather than into the top loops. This creates a raised, textured effect, adding depth and dimension to the fabric. It's commonly used in patterns to enhance the visual interest of blankets, garments, and other crochet projects. Mastering this stitch allows for more intricate designs and variations in crochet work.
From my web site Crochet Cabana.yo, insert hook into the back of your stitch (in other words from back to front), go in front of the post, pull through (3 loops on hook) bringing stitch up to height of previous stitch, yo, pull through 2 loops (2 loops remaining),yo, pull through remaining 2 loops to complete stitchThere is a video demonstration of this method on the web site and at my YouTube channel.
My best guess to what you are asking is that you are referring to Front Post and Back Post stitches. This would mean that you sitch around the stitch below the one that you are making. Either by bringing your hook in from the "front" (Front Post) or the "back" (Back Post). The added Links would be good to view to see what is meant by "Front Post" and Back Post.
Then you have to look at the pattern you are trying to make. The post should always be made on the right side of the pattern for which you are working. If you are making cables for instance, then it is always a front post stitch. If you are making an edge for a blanket or sweater, then it would be every other; so one front then the next back, ect. Hope this helps!
Its not possible to work around a crochet space because a space has nothing in it. However it is possible to work around a crochet stitch such as the post of the actual crochet stitch. You can work a crochet slip stitch over the top of crochet chains and stitches to get to another place in your crochet piece. You can also work crochet stitches around the post of a stitch. The term working around the space does not make any sense and is not good language for describing written instructions.
For a double crochet, you yarn over and pull a loop through the target stitch. There are three loops on the hook, the one you started with, the yarn over, and the loop you just pulled up though the target stitch. Pulling a loop through two loops at a time means two strokes, or a double crochet. A treble builds on this.For a treble crochet, you yarn over twice before pulling a loop through the target stitch. That means four loops on the hook. Pulling a loop through two loops at a time means three strokes, or a treble (triple) crochet. A double treble builds on this.For a double treble crochet, you yarn over three times before pulling a loop through the target stitch for a total of five loops on hook. Pull a new loop through two loops on the hook four times.To put it another way: The procedure is to yarn over three times, insert hook into the indicated stitch, yarn over and pull through the stitch (5 loops on hook at this point), yarn over and pull through two loops at a time, four times.Just as in the double and treble above you increase the number of beginning yarn overs and the number of times you pull through two loops.It seems like it ought to mean 2 x 3 or six loops, but it doesn't. A triple treble isn't 3 x 3 either, it's four yarnovers and five loops.The abbreviation for a double treble is typically dtr.
I think what you might be talking about is the reverse single crochet which gives a corded look. It is generally used as an edging. The method is to work a single crochet stitch from left to right instead of the normal right to left. I did see a video that said it was corded ridge. The demonstration appeared to me to be a front post dc, but I can't speak definitively to that as I'd have to investigate it more.
You can count the stitches by looking at either the stitch post or the top loops of the stitch. Don't forget to count the beginning turning chains as a stitch.