Eve is really good at tutoring people on picture posting. I'm sure as soon as she sees your post she'll help you out. I'm no expert, but briefly, what you need to do is save a copy of the picture (a reduced size works best) on your hard drive where you can easily find it. Click on "Photo Gallery" near the top of the main page and select "upload photos," and then log in. It will give you the option to browse for the photo you want to upload and give it a title, description, etc. Find the photo on your hard drive, upload it, and save it in the folder of your choosing. Then when you create a new post you can select your image in the box at the bottom of the new post screen. You will be able to choose from all of the ones that you have saved in your folders. Preview the message first before posting to be sure that the picture shows up.
I hope that helps. By the way, I think your collared is a really cute girl 
élan
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3.6.0 Collareds
1.2.0 Leopard Lizards
1.0.0 Mali Uromastix
1.2.0 Green Anole
1.0.0 Chinese Dwarf Newt
1.0.0 White's Treefrog
1.0.0 Fire bellied toad
Lotsa Felines
1.3.0 Canines
1.0.0 Equine