If you're getting a filesize too large error when uploading pictures, try reducing their size by shrinking them with some software. The easiest way is to use the fileshrink online software.
You can find it here: http://www.picresize.com
If you have more than one to shrink, try the batch option: http://www.picresize.com/batch.php
It's best to save your pictures as JPG.
Happy posting!