To put a background in a response messege open a second window and go to a background site.
Click on the thumbnail of the background you want. When it opens right click, click Properties. Highlight Address (URL). Right click, Select All. Right click again, select Copy. Hit OK.
Go back to your original site and open the reply window and click on the small, grid-looking icon.
The first frame is Rows and Columns, type a 1 in both boxes.
Next go to Padding and Spacing, type 10 in Padding, leave Spacing at 1
Next is Border Width. You will have to play with numbers to see how wide you want your border, and then click on whatcolor you would like for it to be.
Go to Background. Place your curser in the Background Image Url space and click keys Ctrl & V simultaneously, then Insert Table and your background will appear onscreen.
It will increase in size as you add words, items, gifs to it. You can go inside that background box and create another, as many as you like.