Start by choosing a photo web host. I use Photobucket. It's free.
Got to
www.photobucket.com and register your name, password, etc. Once you do that you can establish albums and then upload photos into those albums. Photobucket then provides you four links to post online depending on the site you're posting at.
Register there first and report back if you hit a snag. As I said, it's free. I've been using Photobucket since I was first online, so years now.
Cheers