Ok, there are a TON of shortcuts in Photoshop. They really can save you time as you work . . BUT.
You probably don't know Photoshop really well just yet. (Hell, I don't!!!) The last thing you need to do is try to memorize what different letters and the shift or control or alt keys in combination with each other might do.
Once you know Photoshop really well, the cool and nifty shortcuts will make sense to you and will be easy to learn. As for right now, though, I'm not a fan of using shortcuts until you can do a function manually and understand how it works.
When you're learning shortcuts, it's best to just learn one or two at a time. Don't rush this, it will come in time. Some shortcuts are simply hitting one key on the keyboard (like "tab" or "Z"), many are combinations of modifyer keys and another key. (Modifier keys are the shift, control/command, alt/option, etc keys.) Something to remember when you're reading about shortcuts from other sources: Windows and Mac have different key names. Ctrl (control) = Command; Alt = Option.
All that said, there ARE a few shortcuts that I think will be very handy for a beginner. We can get into the complicated stuff later. Here are the easy ones.
"control" + "N" = opens a new document (same as File > New)
"control" + "O" = opens a file (same as File > Open)
"control" + "W" = closes the active window (same as File > Close OR clicking the red X in the top right corner of the window.) [it will ask you if you want to save the changes. The answer is probably NO. Think first, be careful, and don't rush through this, or you may save over an irreplaceable file!]
"control" + "Q" = closes PHOTOSHOP! Don't hit Q accidentally or you'll close out of the whole thing! (Yes, I've done this before. heh.)
"control" + "S" = saves the active window (same as File > Save) [This is safe to do when you have already saved the file in a location and with the name you want and you are now saving changes to that file.]
pressing the "tab" key will make the toolbar and palettes disappear! (It hides them) Then hit tab again when you need to view them. (Gives you more space to work with your image.) To do this with palettes but keep toolbar visible, hold down "shift" + "tab."
"F7" will hide/show the Layers Palette (it will open it if it's closed!)
"C" makes the Crop feature active
"M" maes the Marquee Selection active
"T" makes the Text option active
"V" makes the Move Tool active
"Z" makes the Zoom Tool active
"control" + "M" = opens a the Curves adjuster (same as Image > Adjustments > Curves)
"control" + "L" = opens a the Levels adjuster (same as Image > Adjustments > Levels)
"control" + "B" = opens the Color Balance adjuster (same as Image > Adjustments > Color Balance)
"control" + "U" = opens the Hue/Saturation adjuster (same as Image > Adjustments > Hue/Saturation)
"control" + "R" = shows/hides rulers
Those are the ones that I use the most right now. I'll post an entry in the future with others. If you know of any shortcuts that are useful for a BEGINNER, you can put that information in a comment.