Here's something I cut and pasted from long ago. The basics are still the same, but certain things like the 1MB file size have changed. You can now upload much larger files. Hope this helps...*
Do you have scans, pics ready to post? If so, try to get their sizes pretty small (like about 1MB or smaller) so they will readily load up on the site. Then (as you are typing your message) click the 'paper clip' icon on the page as so (highlighted in blue)...
stepone.jpg
Which will bring up this window...
steptwo.jpg
Hit "Choose File" and find the image(s) on your computer that you want to post (the screenshot shows that I had already uploaded the 'stepone' graphic) and then hit "Upload."
When the file uploads, go back to where you were typing the message...
stepthree.jpg
And then hit that paper clip again to choose the file you want to add to your post...
stepfour.jpg
And BOOM!! that's it. There are other ways to upload pics, but this is the most straightforward.
*
(Technical note for clarity: a couple of minor revisions were made to the text after I took screenshots, so some of it doesn't match exactly.) (Of course, now everyone reading this is trying to find those differences. Ha ha.)