I think there are instructions within the 'New members' section but...........
1: Sign up to Photo Bucket
2: Click on the large blue box that says 'Upload' and select the photo/s you want
3: Once its uploaded click on the image and then at either the bottom or the left of the screen there should be 4 x boxed with various headings such as URL, IMG etc.
4: Highlight the IMG (the bottom box) and then copy it with a right click.
5: Post what ever your going to post and then copy the IMG code from Photobucket into the same place. It should come up with something in brackets. Post your post and it should work.