there's two ways...   ok follow  me here |^|  see the little yellow box with the mountains  in it ....thats the insert picture box icon    ..................................................  .........
 
thats where you put in the code for where the picture is so it will post..
it can be 
on your computer or uploaded to a free photo bucket account  and thats where you use that button....  so you can link it from your photobucket account to S-B
 
otherwise you have to use the old method 
and upload it with the managing attachments 
and here's the tutorial in pictures for that for that.