Having trouble posting pictures

It always says that they need to be 100x100 or that tsomething is too large. Why is it so complicated?

100 x 100 is the width/length of an avatar (the picture beside your name) but it also has to be under a certain kb...some formats can be small in size and still pack some weight in the size.

If you are using a jpg, it probably will work. PNG, MAYBE, but BMP NO WAY...too fat.

Oh and the size of 100 x 100 is very typical of forum format.

I have the same problem and all mine are jpg.  Of all the pictures I have on my computer, it let me only upload one of them.