When you hit reply to a post or start a new thread, it takes you to this box where you can type in your message. You need at least a few words in there or it won't go through.
Scroll down to the next section, called Additional Options. There's a button labeled 'Manage Attachments'. Click on it. This will open a popup window. Make sure you allow popups from this site.
It will give you the option to upload a file from your computer. Hit the top browse button. Find the 'My Documents' Directory, Then the 'My Pictures' sub-directory, then find your file, 123.bmp. Click on it.
Now the name of it should show in the little title window right under 'upload a file from your computer'. Hit the upload button and it will start doing it's thing. I have found that if you only upload one picture per post, you will see the picture in the post, but if you do 2 or more, they only show up as links.
If you get an error message that the file was too big, you are going to have to resize it in MS Photo Editor or another program. File size is 100KB max. Rename the file after you resize it and go back and do all these steps again. You can run your cursor over the resized file to see how many kbs it is, so you might have to resize it again if it is still over 100 kb.
PM me with your phone number and I will walk you through it if you still have trouble.