There must be some fancy trick to sharing pics. Most pics are rejected when I try to attach and when I insert a link I can see it and it later goes grey... oh well. The pic above may be the only one I ever post.
I believe the most common problem is exceeding the 500K-per-post limit for photos (that's per post, not per photo). The trick is re-sizing photos so you don't exceed that limit. Unfortunately, resizing works differently on the various operating systems and may not be easy. (If you happen to be on a Mac, you can use Preview | Tools | Adjust Size to do it). Also- it's a 500K per post limit so you start with another 500K in each new post.