yes to add to what bertieg was saying,
when you post a message you will notice just underneath where you are typing that you have Options & then Attach file.
I think the bytes is off a little (lol) cause you can't really upload a 20MB+ file here, but if the file is around 2.5MB or so (smaller) than you should be able to upload them by using the Browse button located there.
Just hit it & find what you want on your PC & hit the submit reply button.
All done.
Good luck
PS
you will notice you can only upload certain file extensions under it