You asked how to get rid of ants:
Here are a few hints -
1.  Check to see that they are not _living_ in the hive, but robbing the
hive.  If they are living in the hive, you will have to remove the portion
of the hive that they are living in, then cure the infestation.  Unless some
other member of the group knows of a way to remove the hive.
2.  If they are infesting/robbing the hive, check the archives for methods.
There is lots of information that was helpful to me when I had the same
problem as a beginning bee keeper.  (I still feel like one!)

I had a nest of small ants that had eggs under the top cover of one of my
hives.  I painted the ants and eggs with mineral oil and was rid of the
problem. This happened while I was out of town on business.
I also had a nest of ants that found the honey irresistable - their trail
was easy to find; however, I advise watching for poison ivy when following
an ant trail.  Adrian Wenner had some great information regarding safely
getting rid ants.  Also in the archives.
My hives were healthy during this problem(had problem during spring flow),
but the bees were testy.  The bees will appreciate being rid of the ants.

And - I appreciate the suggestion of mineral oil instead of used motor oil.
My mentor paints all his stands with used motor oil regularly.  I don't like
to see the oil slick running down the creek from my hives, and have avoided
this method when possible - which is always, now!

Best wishes to a rapid riddance to ants!
Tim Rich