Hi Vanessa! Welcome to DPF!
To add pictures (assuming that you're trying to upload it from your computer):
1) click on on the "My Profile" button at the top of the page
2) you will scroll down where it says Albums on the left hand side, press the "more" link to the side of it.
3) click on "Create Album," Name it whatever you want but leave it public, then click "Save Changes"
4) There will be a box with "Album title," Click on that and from there there will be an option to the side to add photos.
5) Click on Add Files to the side
6) Upload the pictures that you want, make sure that the pictures dragged to the bottom so it loads in the album
7) Save pending pictures
8) From there click on your album again and then the individual photo.
9) There should be the photos URL address and BB Code([ img ]photo link [ /img ]), Copy the BB Code link
10) Reply on the thread, paste the BB Code and the photo will appear when you post.
Credit for the above goes to coblj003, who kindly posted this for me when I couldn't figure it out.