As you can probably quess from the question, I can,t seem to figure out how to fill in the missing tripod leg in my logo, once the circle part has been removed.
Remove the circle part, then clikc with the hollow arrow tool the stump points and drag them to the final destination.
Learn how to use the Pen tool.
Learn how to use Pathfinder.
Yours is a very simple job and your question indicates that you are very unfamiliar with Illustrator.