I'm on my iPhone and it looks like the picture posting process is the same:
Click on the paper clip for attachments
Click on Choose File > Upload
Select photos from your photo library.
If your photo size are as large as mine (1MB+), you can try to take screen shots and upload those instead. If those are still too large, then you'll need to use a resizer app, something like this:
https://itunes.apple.com/ca/app/imag...670766542?mt=8