The iFrame hosting means that I'll create a small page that you install into your existing Yahoo!Group. If you can copy and paste, you can make this work!
Here are the steps to getting a hosted WebRings page
Complete the form below (if you do not know the U#, leave it blank and I'll find it)
Wait for a confirmation email that will contain the "official" URL for the location of your WebRings
Be logged into your Yahoo!ID then go to the homepage for the Group you are trying to register
In the left column, click the link for "Management" at the bottom
Under "Group Settings", select "Description and Appearance"
Click the "edit" link just after the word "Description"
Paste the copied iFrame code, then save.
You may have to make some adjustments to the width and/or height attributes for proper layout, just be sure not to shrink the box so small that it cannot be properly viewed.