Using a photo host

Ok, Iv'e exhausted all efforts on what is most likely a easy process but here goes. i joined a fishing forum, they ask that you transfer pictures from a 'photo host'. I have an account or am registered with photo bucket. I upload the pictures from iphoto, follow all the instructions on the forum on how to post and i get a message stating the picture is too large or must be in .jpeg format. The picture says it is in .jpeg. The routing number or sequence of numbers doesn't seem to be correct. Editing the pictures doesn't help.
What should i be reading to help me with this process. I enjoy the challenge of figuring things out but have hit a wall. Thanks for your help guys..

After I posted this I went on photobucket and they have changed some things around and i need to re register. That may be the problem. Let me see how that goes. I guess they have upgraded their site,