Posting pictures can be still done with traditional film cameras, just takes a bit longer to get them from event to post and my sincere apologies if you already have a handle on all this. I wasn't certain if the comment was about general confusion over the process....
Take your film to be developed but also ask for a CD version of the prints ( some places will even store them on an on-line server for you )
Once you have a digital version of the shot you want to post, you will use some sort of photo editing software ( might come with the CD ) or the on-line host. The reason you want to edit the file is to make the size managable by reducing the size to let's say a 3 x 5 and a modest pixel count of 150 ( this makes the picture easy to read on the screen and download faster ) You can also do stuff like adjuct brightness & contrast if you want to really start messing around.
The last part is making sure the file is available somewhere out on the web because when you post your message on the forum, you don't actually include the whole file in the message. You are inserting a hyperlink that the BB knows is an instruction to go look for the picture on an outside server and show a copy of it whenever someone looks at your post.
There are a number of photo web hosting sites out there, perhaps some of the other members that post pictures could suggest a good one. Your ISP may offer you some server space as part of your monthly agreement, if so you can follow thier instructions for how to upload files from your home PC to their server an you'll be all set.