Welcome to the QB, Rainey. It won't take you long to learn your way around this place. Maybe I can help you with posting a picture. I'm a year older than you and not super computer savy but I'll try.
First, the picture can't be too big. I'm not sure exactly how big is too big but I tend to reduce my pictures maybe half two or three times. It all depend upon what camera you are using and your computer I suppose. Just reduce your picture if it tells you it can't post it or it doesn't post it.
You have to be in the advanced reply mode to post a picture so click on 'go advanced' and when you are in that mode and advance down below the box where you're typing in your message, you'll come across, 'manage attachments'. Click on that and a browse window will open up where you can select your picture from your computer (reduced in size of course) and then click on upload. You will see your picture info show up on that browse window. It will be added into your post at that point. You won't see it until you preview your post or you post it.
Hope that helped. Do try again and if you have questions, just ask. Someone will help you if I'm not around.