Use Imageshack (http://www.imageshack.us) instead, if it's under 600 KB--which, if it's an avatar or sig, it probably is. And it has to be png, jpeg or gif. I use it for most, if not all of, my stuff. Well, everything not on DeviantArt.
Anyway, avatars and sigs. Okay. It largely depends on what program you use. I have Paint Shop Pro 7, you can download a free trial of that or version 8 at Jasc's homepage (Google it, it's probably Jasc.com or something). If you keep resetting the computer clock every time you use it you can keep it forever. Steal of the century, especially if nobody else uses your computer and won't care about the time discrepancy.
(If you want, also download Jasc Animation Shop. You can make animated avatars that way, but that's something for another tutorial.)
I make all my avatars myself, so lemme do a quick tutorial or sumpin'. Unless noted, everything will be done in PSP7.
I'll make an avatar for myself from
this picture, taken from the
pop'n music 10 Murmur Twins character page. That's not really important, just provided for credit.
Avanti!
Step 1: I'll copy the picture into Paint Shop Pro 7. Easy easy, right-click, select Copy, and go to PSP, right-click and do Paste. Hold down the button or whatever if you're using a Mac. I don't use 'em, so sorry if'n this is confusing.
Step 2: Cropping. I can't use the whole thing as my avatar, duh, so select the Crop function. You can see it highlighted in
this screenshot. Click and drag to make a square of the appropriate size, then double-click on it and it'll delete everything around the square. Crop once, then zoom out and see how it looks--I made it too long in that picture, so I cropped it again to make it 55 x 55 pixels. Resizing pictures this small isn't a very good idea, so I usually rely on imaginative cropping to make it small enough.
Step 3: Customizing the picture--text and decoration. Since I "draw" my text onto the picture instead of actually using the Text function (I can squeeze in more words that way), make a new layer. Go to Colors>Increase Color Depth>Increase to 16 million colors, then go to Layers>New Raster Layer on the Toolbar. You can name your layer something new if you want. For the purposes of this demonstration, I'll name the top layer Layer1.
3a. In Layer1, I'll zoom in a bunch and start customizing the image using Paintbrush, 1 pixel, 100 opacity, color white. You can see in
this shot how I've started. Decorations on the border make me happy, and the little bracket thingies look like they could house some text pretty well, so let's go to 3b.
3b. So I drew some text below the brackets, also in white. Unfortunately,
the text is off-center, and you can't see it very well. Let's fix that. use Selection and drag it so you get the text in there, then move it appropriately. Since the text is on a new layer, you won't move the background image as well. That irritates me the hell out, when that happens.
3c. Fixing the color. Pretty easy, just use Flood Fill (REMEMBER TO SET IT ON "RGB VALUE" FOR THE MATCH MODE OR ELSE IT WILL FILL UP THE ENTIRE PICTURE) and change the color of the white spots. While I'm at it I'll add a little mini-bracket below the squares to the left to make it even. Evenness is my best friend. *OCD OCD* So anyway, I filled it up with varying shades of teal or whatever the hell it's called. Experimentation is your best friend--if you try one color and it doesn't work out, try a few others, or different shades of that one. Just make sure to pick something that will be visible and aesthetically pleasing. Here's a
screenshot for your troubles. I could do some more on the bottom of the picture, like my name, but I think that's enough. This is getting a little long.
Step 4: Now that we're finished with most of this, let's fix the colors, flatten and save. Go to Colors > Decrease Color Depth > 256 Colors. For this picture it doesn't matter what method you use, but my default was on Optimized Octree so whatever. Go to Layers > Merge All Layers. This "flattens" the image so that everything is on one layer. You can't save it in a GIF if you don't do this. Now go and Save As as a GIF (NEVER EVER EVER save avatars as JPEGs. They make it ass-ugly with compression and kill your family and friends.).
Final result:
So there you have it. I'll expand a bit if you wanna hear about how to make portions of your picture transparent, animated, whatevas.