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
You can see layers in document in LAYERS palette, go to Window > Layers if you do not see it on the right side of screen. If layer is not visible then eyeball icon on the left side of layer thumbnail is hidden, click where eye icon suppose to be to show eyeball icon and layer content. Visible layers have eyeball icon on the left side of layer thumbnail in LAYERS palette. Another way to show layer content is to click on layer then go to Layer > Show Layers.
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.
color layers is simply color layers
Open the Layers window.
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.
One layer.
To store image parts.
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.
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.
Don't know how it actually does it, but you can only save layered images in format that supports them. ie: photoshop native files .PSD or layered TIFFs. Jpegs can not be saved with layers.
The Move Tool allows you to rearrange layers in Photoshop by dragging and dropping.
layers are separate images stacked one above another, layers can have transparent areas so you can see content below