Ed,
The secret to posting pictures is to open two windows at once; one points to the thread where you are adding a post, and the other points to your Album. Start your post and when you want to add a picture, switch to the other window. Once you find the picture you want to add from the thumbnails (you may need to go to other pages in your album), then click on that picture. A larger image appears and below it is a series of menu buttons and picture insertion options. The menu buttons allow you to manipulate that picture and is self-explanatory. Below the picture caption box is an area titled "Direct Links" or "BBCode Links", depending on how the preference is set for you Album in your personal profile. Most are preset to Direct Links and that is how I will explain it below.
The instructions tell you what procedure to follow and there are 3 picture options that follow with "code" in the boxes to the right of each style. A "Best Size" picture is good for one or two pictures in a post, and a "Thumbnail" shows just a thumbnail-sized picture. Select the code in the box for the picture size you want with your mouse cursor and it gets highlighted. Press CTRL-C (for copy) to place this code in the Windows Clipboard buffer. Note the little picture icon in the instructions that is yellow and has a mountain and sun in it for the next step.
Switch windows back to your Post. Move the cursor to the insertion point and click to anchor it. Now click on the yellow "Insert Image" icon you see above the text window and a new window opens asking for you to provide a URL for the picture. Press CTRL-V to paste the Clipboard contents into the window and press OK. The picture is now inserted into your Post.
If you have lots of pictures to add to a Post, switch back and forth between the Post and Album windows, selecting new pictures each time. At the very bottom of a selected picture in your album view, you'll see a separate picture box that says "Linked Thumbnail". Select the contents there and switch back to your post. Don't use the yellow Image Insertion Icon, but just paste that code into your thread where you want it. The code will appear, but if you preview your Post, it changes to a thumbnail in the Post, but will expand to a medium picture when someone clicks on it in your thread.
Hope this helps.