My suggestion and it is very easy. Use photobucket.
1. create account with them
2. Upload the photo to photobucket
3. click on the picture you just uploaded in photobucket
4. click the IMG link that is either below or to the right of the picture. It will auto copy it
5. Create your THO post and paste the link in the body, the picture will be there if you preview or post.
and that is it.
I hope this helps
Jason