In the layers pallet (usually this will be at the right side of the work space) select the layer you want to lock. Above the layers list you will see the word Lock and several icons; you can lock transparent pixels, lock image pixels, lock position, or lock all.
If the layers pallet is not visible go to the top menu and select window and then layers.
(the hotkey for this is F7)
This is for Photoshop CS4, an earlier version may be different
There are many resources and websites that offer information about Photoshop layers. Some of these websites that offer information are Adobe, Photoshop Essentials and Photoshop Cafe.
Photoshop layers may not import into After Effects if the file format is not compatible or if the layers are not properly organized in Photoshop. Make sure to save the Photoshop file in a format that After Effects supports, such as PSD or TIFF, and ensure that the layers are named and organized correctly for easy import.
Open the Layers window.
color layers is simply color layers
Yes, .psd files maintain the layers you create in Photoshop so that the next time you open your .psd file in Photoshop you can continue to work directly onto the layers.
To store image parts.
One layer.
To select all layers in photoshop for a PC open up your layers window (It is under window - layers), hold down the shift key and click on each layer that you want to group together or edit.
Flattening layers just merges all layers down into one. It reduces file size, but once the image is saved and Photoshop is closed, you will no longer be able to undo the change and edit those layers separately.
To manually align layers in Photoshop, select the layers you want to align, then go to the "Edit" menu, choose "Align" and select the alignment option you prefer, such as aligning them horizontally or vertically. You can also use the Move tool to drag and position the layers as needed.
I opened a new project in Photoshop Elements 6 and began adding layers. I'm at over 360 and it hasn't stopped yet :D My guess is, it will add as many layers as your computer can handle without crashing.
The Move Tool allows you to rearrange layers in Photoshop by dragging and dropping.