put the photos you want to upload on the computer's desktop, because they'll be easiest to find there. When you are creating a post, you'll see the "Insert image at Cursor" button just above the right hand side of the text box. Click that, and it will open up a window that has a button that says "choose file." Click that, and another window will open. In this window, you can navigate to different places on your computer to find the file you want. In this case your photo will be on the desktop. Select the photo you want, click "choose" (at least it says "choose" on my Mac), and that window should disappear, taking you back to the window where you clicked "choose file." Now hit the orange "Upload Image" button. It may take a few seconds, but soon some text will appear in the text box of your BPL post. That is the textual representation of your image you just uploaded.