Hm. You probably want to learn the basics first eh? Once you get the hang of photoshop, its really easy! So no saying your 'stupid' only I'm aloud to call myself that heh.
http://unavoidable.net/adobebasic.htm I made this tutorial a while ago which absolutely no one uses..-cries- which how to use all the basic tools. So that might help you a little to get started (not sure if you knew thatmuch or not..I'm just assuming you've never used it before???) Anywho. The first step to making a sig, let say a simple version of what PCB did for you in your sig. Gather all your images, of course. Now, you can do what PCB did, and have a white background which is easy enough. Simply make a new image (whatever size you want your sig to be) and pick white under the 'contents' part of making a new image. (file - new) Or if you want a BG, like I have, simply find one you want, and have it open and ready for when you need to use it. Now its time your crop your images. The polygonal lasso is a good tool to start off with for this. Only its most likely set on lasso tool right now, so click and hold that lasso button on your tool palate till 3 options pop up. Just pick the polygonal tool *use the tutorial if you need help here, it shows the diff tools*

So now your ready to cut out your image! Go to your first image, lets say one of your birds you want in your sig. Use the lasso tool and click all around the image till your back where you started, it will then join up and make a marquee around the part you cut out (so you get only your image, not the BG) Now. Copy it (ctrl c) and go to your bg image, whether it be white or an image and hit ctrl v. This will paste your image onto your new bg.

(BTW, you can also do it like PCB did. Use the marquee tool and select a circle or square or what not around the bird or whatever you want in your sig. Do the same thing as other option (ie: ctrl c, ctrl v)

Now, with either one you desided to do, this step can/will apply to both. You probably want to smooth the edges a little. I start by using the blur tool. Just use it and go over all the edges. This will kinda blend it together with the bg a little making it cleaner looking

Now if you want, you can take it one step farther and use an option called 'outter glow' (one of my fav tools ) To do this, go to Layer (at the top) layer options - outter glow. Play around this this. The settings I usually do is something like. blend mode: normal opacity: 70-100% depending. and leave the rest unless you want the outter glow bigger or smaller. (also pick a color you want)

Thats pretty much the basics to it. Not sure if it all made sense as it does to me seeing I've only done it 50 million times. So let me know if it doesn't and I'll try to go more indepth. It takes time I guess, but you'll get use to it. Its a great program. Really hope I was of help!!

(sry so long..)