This is actually a very good question, as most people make the mistake of using sandbags when sighting in an air rifle. The question is, what type of air rifle? If it's a springer, you want to hold the gun in a relaxed way. If you hold it real tight against your shoulder, it will be hard to sight in because of the unique recoil. The same goes for sandbags with a springer. If you are going to use sandbags, put your hand underneath the forestock in a relaxed way. Also, get a scope stop, so that you can stop "scope travel" which tends to occur with springers. As for PCPS, and pumps, there is no recoil, so you can pretty much sight in like you would a firearm.
Your shoulders determine where the ball is going to end up. Your foot placement also matters. Your eyes will deceive you when starting to play. I suggest lining up to tee off. - then placing a Golf club on the ground (don't move your feet when doing this) behind -along your heels. Step away from your club and back away from the green or fairway. Notice where your club is pointing and that's where you have aimed your shot in golf. Once you correct your foot placement most of your shots should be down the middle of the fairway.
It's different for every one. For a pistol, you'll pull back the slide. For an M4, you'll pull back the charging handle. For an AK, you'll pull back the bolt. For a sniper, it's a typical bolt action. For shotguns, you pump it. It's pretty simple.
On cheap guns, you want to keep both eyes open, with the gun pointed forward. after you shoot, watch where the bbs go, and adjust from there. For mid-range guns, often the Iron sights will be usefull as starting points for aim, as well as function in close ranges. There are many styles of iron sights, but the basic principle is that you look through the rear, and line it up with the front to make a sight picture you can move onto a target. guns with magnification optics require you to close one eye and aim throught the scope. If it is set up correctly you should hit near the crosshairs.
check the link below and contact customer service. Crosman list that some parts are still available for this rifle.
It depends on which model you are talking about. Benjamin has made over 70 different models over the years.
I recommend checking online for videos and forums to assist you in setting the sight for your rifle. With each rifle and barrell, it will differ on how the sight is set and someone with more knowledge may be able to assist you.
You sight it to a specific range , e.g. 100 meters. Clamp the rifle to a solid object, or use a benchrest. Shoot at a target and adjust the sight accordingly, until the holes in the target zero in to the sight.
Assuming you mean a Mauser 24/47, use the sight as you would any open rifle sight. The slider on the rear sight adjusts for range- marked in meters.
Crosman still has parts for this rifle. contact Crosman at the link below (Customer service) and order the parts you need.
adjust rear sight up for distance
Should be a Stevens rifle, but the peep sight would probably be aftermarket. If you can send a digital picture of the rifle and a closeup of the sight we can probably ID it for you. email@example.com
The same as you would any other rifle.
It would be considered fair condition from your description, and worth between $55 - $75. Depend on the rest of the condition of the rifle.
You need a gunsmith.