how can I input an avatar image?
I've been trying for days but all my saved pictures are not accepted.
As Jediferret said, there's a limit on both image size and file size. It's actually a real pain getting a standard icon down to under 10 Kb -- not only that, most icons are 100 by 100 pixels.
Quickest technique I know of in Windows (the image will be crappy, but it's better than nothing):
Open the source picture in Paint. If you don't know how to do this: right-click the image, select "Open With", select Paint.
In Paint, the image will probably be so big you can't see it all. Go to View and select "Zoom out". Zoom out until you can see the entire image.
Most images are not square, so you need to choose a square section of your image to turn into an avatar. To do this, go to View and select "Select". You can now draw a square on the picture, which will select that part. Don't worry, for now, about the image size; just find a good part of your picture.
If you choose a square section and you decide you don't really like it, hit Esc (Escape) and try again.
Once you've selected a square section, hit Crop. This will crop away the rest of the picture.
Now, resize the image: hit Resize. This will open a little box. Choose Pixels (rather than Percentage), and type "90" into whichever box has the larger number.
Go to the File menu and choose Save As. Save it as a .jpg.
The image will almost certainly be small enough, as a file, to upload for avatar use. If it's still too large, post in this thread again, and we'll tackle the challenge of compression.
The lovely thing about this process: it's fast, it's easy, and it uses standard Windows tools. If you don't like your first results, just try again. As long as you used Save As and not Save, your original picture is still intact.