Change the 2's to 1's (as shown) then click "Padding and Spacing" and this window will appear:

Change the numbers from 1's to a 7 and a 0 as shown.

Next you need to determine what kind of border you want. Click on "Borders" and this window will appear:

You'll notice I've chosen a width of 2, which means two pixels wide , but it can be any number you want. Then click on the color you want the border to be.

Now it's time to decide what picture you want to use for a background. It has to have an actual address, so I recommend using one from a Groups album. You can use anything from here or any other Group you want. One thing, though, if it's a big picture, you may end up with only a picture and a half, because it will automatically repeat to fit the table you're making, so smaller is usually better (also a low-byte pic will load faster). However, if the picture is the right size, you can use a single image for the entire background.

Go to the album of your choice and the page where the picture is and right-click on that picture (not the thumbnail of it, the actual picture). This window will appear:

Highlight the URL (address) as shown, starting with http:// and going down and to the right. There is more address than you can see, so make sure you get it all. Then right-click on that highlighted address and choose "Copy" from the pop-up menu (or hit Ctrl+C on your keyboard).

Now go back to the message editor and click "Background" and this window will appear:

Put your mouse cursor in the little window marked "Background Image URL" and hit Ctrl+V on your keyboard. That will paste the pic's address in the window as shown.
Now just hit "Insert Table" at the bottom and the table will appear on your message. It will start as just a tiny square, but it will grow as you type in your message or add other pictures. To type in the table, place your mouse cursor in the middle of it first. That's it!
Once you're accustomed to the controls, you can click the HTML box at the bottom to change the table's values (padding, spacing, border size & color, etc.) after the table is created. Also you may want to start a collection of pre-saved addresses in plain text file i.e. notepad to make the process much easier.