Just in the forum main page there is a start new topic button up the top right. when It go's to the page where you right the topic and content and sutch there is 4 buttons in a row with the folowing icons on the (chain)(envelope)(picture)(picture+'manager'). click the one with just the picture (3rd button)

You need to upload pictures to a sight sutch as 'photobucket.com' as the pics need an internet address..