Do this:
Go Advanced
On next page, click on Manage Attachments
Box opens up-- click on +Add Files
Then click on Select files
After selecting the file from your computer, click on Open
Then click on Upload files
Type the text for your post in the box, and when you preview, you should see your photo.
Then hit "post" and your post should have the photo.
There is a size limit for photos. Try not to post huge ones.