I use imgur to post pictures from my PC. Assuming you are doing the same, the steps are:
Log-in to your account. Hit the "add images" button and then go to your pics file and upload the ones you want to imgur. You should be able to use the drag function or the browse function by double clicking the picture. The pics should load into your imgur gallery and should show up there.
In the gallery, double click on the pic you want to post and the pic will come up with a menu to the right with several options and a list of picture sizes below that. Hit the picture size you want (medium thumbnail is usually about right, I think) and then hit "copy" next to the BBcode box that indicates posting to forums.
Come back to OG and hit the reply box to whatever post you want to post the pic to. Right click copy in the reply and it should show the picture "address" in the reply. To confirm that it loaded properly, hit the message preview button and it should show you how the pic will show up in the message. If the picture is too big or too small, delete the picture in the message box, go back to imgur, and choose one of the other thumbnail sizes to increase or decrease the size of the pic.
Hope this is not too confusing and helps,...and good luck! If you try it and it doesn't work, explain where the hang-up is and I will try again,...or maybe someone else that uses imgur can explain it better.
