Martha, there should be a "Reply" button at the top and the bottom of whatever page of the
Sandbox III that you have open. The earlier Sandbox topics I and II are locked.
When you embed a photo from Flickr, you do not use the "insert image" button (the little picture icon above the reply box.) You just copy the BB code from Flickr and come back here and paste it into your post. When you click "Preview" or "Post", the image will appear.
To clarify, follow these steps and you should be successful:
1. Above the Flickr photo you will see "Share". Click on that.
2. Select "Grab the HTML/BB code" from the drop down menu.
3. Click on the "BB Code" radio button
4. Copy the code that appears in the little window
5. Come back here and paste that code in your post.
6. When you've finished typing your post with the photo code, click "Post" and the photo will appear within your post.
7. You can also check your post by first clicking "Preview" to see if the photo shows up the way you want it to. Make any changes to your post, then click "Post" and the photo will appear within your post.
The photos from your website have .jpg at the end of their URL (photo's web address). With .jpg files, you have to use the insert image icon, but not with Flickr because it provides the BB code instead. Flickr tried to make it simple, I think, but until you get the hang of it, posting photos from there can be a bit confusing, especially if you're used to posting photos that have .jpg endings from other websites. Don't give up!

HTH,
Kathryn