To report abusive or offensive posts, and also spam you just need to click on the triangle towards the bottom left of the posts, highlighted in this picture with a badly drawn yellow arrow, add a reason why the post is being reported and just click send, this can also be used if you do a double post and want one trashed, please include a reason unless that single post makes it obvious that it should be in the trash, the reason for this is that the message is sent to the mods room but only with a copy of that single post.