Ok,youve already uploaded to photobucket.
In photobucket put your mouse OVER the pic you want to insert in your post.
UNDER the pic will show a few columns downwards,Click on the DIRECT LINK one and it will highlight blue,right click and "COPY".

Go to the forums and in the POST page Click on this ICON


Delete the HTTP thats already in the box that opens and PASTE the DIRECT LINK you copied earlier. Click ok and presto.

Scroll DOWN to the bottom of the pic once its in the post page and add next text or pic as required.

HTH Cheers Rod