Since you've already got them in your album:
This is how to add photos to your post using the site's photo album:
1.) Login
2.) Go to My Account (may have hit Home button first) and mouse down to Album.
3.) Choose Upload Picture (navigate to photo you've given a sensible name to), be sure to then hit Upload.
4.)
Go back to Album, click on thumbnail to open full size image.
Right click (Windows); Control Click (Mac) and select "copy image location" (its URL).
5.) Return to your reply window in the thread and click on the
IMG button at the top of the compose window.
7.) Paste the image location into the window and click OK. (You can paste over the existing http://)
You can disregard the following, which is posted for general information, not needed in this specific case:
Images tend to be smaller than hosting site's size, but can be full sized if you remove the pixel limitation, (-600x360)— the numbers and the dash preceding, leaving no spaces, and ending in .jpg
An example, of a thumbnail named "hms-penzance-1940...." followed by "-150x100.jpg" is the name of the photo in my album, and it's the "-150x100" that limits the size.
If I remove the numbers, it goes to whatever size at which it was uploaded, subject to web sized image limitations.