I've never used snapfish, so can't help you there.
Photobucket is my preferred choice, precisely because it is so easy to use;
Using photobucket
1) log into your own photobucket account
2) place your cursor onto the picture you wish to post within the topic on this forum, you will see four options appear
3) right click & copy the fourth/bottom option (IMG code)
4) paste the link into the posting
Your picture should now feature in the forum posting.
Remember, if you move or delete the picture within your photobucket account then it will automatically be deleted from this forum.
..not sure if snapfish works in a similar way ?