Creating Your Own Icons in MS Paint
Open up MS Paint by going Start>Programs>Accessories>Paint.
Put your mouse cursor over the little black square on the bottom right-hand corner. Your cursor should turn into a little arrow that's leaning sideways, you could say.
Click on it and drag it to a size so it's something icon-sized, like this:

View>Zoom>Custom
Select 600 and then click on OK. (If you want, you can even do 800.)
Next, hold down Ctrl on the keyboard and hit "G". This will show you a grid, as in this picture:

Using the tools on the left and the colors on the bottom of the screen, create your icon, but remember: this is zoomed in!

This was created using the circle and line making things, as well as the paintbrush.
Now, as you notice on mine, there's an extra row of pixels at the bottom. Pixels are little tiny dots that make up a picture. You can click and drag any of the little black squares to resize your image, as I have done:

That's it! Now, go File>Save As...
Browse to the location you wish to save your icon to.
Name it ICON.ico
You may put anything you want in place of ICON, but it MUST have the .ico in order for this to work.

See where it says "Save as type:"? Make SURE it's on 24-bit Bitmap (*.bmp,*.dib)!!!!!! This is the other part to making it work.
Hit Save.
Now, open up the folder in which you saved you icon, and there you go! It's all ready for use!
....But now you want to use it. Here's how:
Oooooh joy... First off, you can ONLY use an icon on a shortcut.
Right-click on the shortcut.
Click on "Properties".
Click on the button on the bottom-right that says "Change Icon..."
Click on "Browse..."
Browse to the location of your icon, and select it.
Hit "Open".
Next hit "OK".
Again, "OK".
That's it! You've now successfully installed your icon!