As Borgcymru says join
http://photobucket.com/
You then need to upload pics from your pc to photobucket
Whilst in the my album page of photo bucket
1. click the 'browse' button, this will allow you to find the pic of your choice
2. then click 'upload' wait for pic to upload to photobucket
3. then left click the IMG code, which should be underneath newly uploaded pic, it should highlight in blue, right click and choose copy.
4. Go back to your 'reply to thread screen' , left click and paste the IMG code into the post.
5. Preview the post to make sure pic is correct, I'm sure you know the rest
6. Wait for compliments, sarcasm and indifferences to appear in the thread.
p.s. if you want to insert multiple pics just copy and paste each IMG code into the same reply screen