Just save the picture you want in My Pictures, or My Documents. Open up "Paint"...open the file in there,and use the stretch/skew tool under the image bar. It has 100% in the boxes. re-type 50% in th horizontal and the vertical. that will shrink the pic so you can post it. They have to be under 100kb...I think. Keep shrinking the pic untill it will fit. Do the same with your avatar. the avatar has to be alot smaller than the posting pics. Under 10kb...I think
Oh...amke sure after you shrink the pic, you do a " save as" and save the file as a jpeg...other files are the wrong format for posting.
When you wanna post click the embed pic in post box...and then click to upload. There is a testing forum for you to practice on.