Click on "User CP" at the top right of the screen. To open your User Control Panel.
Scroll down to "Attachments" in the column to the left.
Do you see your attachments?
click to open.
Right click the picture
go to properties
copy the URL
now type
and paste the url
and type after.
Like Nemesis67 and Dennis112 said, go to PhotoBucket and open an account.
It's free and you can upload a bunch of pictures there and link them directly
into the thread.