If your using photobucket copy and paste the link that has IMG at the beginning and end then change the IMG to img (upper case to lower case).

Otherwise if you want to copy from your computer when you hit reply below the box you type in you will see Choose File. Hit that then find the file ( i usually put them in a specific folder on my desktop).

When you choose the file then hit upload to the right of Choose file (file must be less than 200kb). Repeat that process till your done then hit Submit as usual.

P.S dont tick the boxes of uploaded files it will delete them. Cheers hope that helps i can talk you through an example over the phone if your stuck. Cheers Andrew