Here's how to post pictures. It's a two-step process.
While you are posting, scroll the whole screen down to a section called "attach files" and click on the button that says "manage attachments." Choose the files you want from your computer, up to four at a time, then click "upload."
Now, here's the trick. They are not in your post yet, but waiting in a queue. So scroll back to your post and put the cursor where you want a picture. Then go up to the little paper clip icon, click and drag down to the picture you want. You should see an attachment link pop up in the post. Do that for each picture.
Hope that helps!