the best thing to do to upload a piccie in the gallery, is to click on upload picture, then it will take you to your picture files, you then right click on the picture you want, and a text box comes up, this should have resize picture, click on theis, it should then come up with a text box sayin, small, medium, large and custome, click on custom. you can then type in the desired size, have a play around to see what the largest size you can go up to, i know when i uploaded a pic of my stilletto nails yesterday, i changed the size to 300 by 400. i beleive the picture has to be under 70 pixles in order for the site to hoast it.
hope this helps, and you can understand my ramblings!