How do we fix the radon level in our home?

Hello,
My husband and I just bought our first house and we have been living in it for about 2 1/2 months. When we had our inspection, we had the radon tested, but we didn't find out the results until we already had a contract on the house. I think our level is 6 or maybe 6.1. First, we want to fix this ASAP. What shuld we do first? I have been reading about it and I am totally confused and really, really scared. I know that we have at least one sump pump. Would capping this be a good idea? Also, we seem to have moisture in our basement, would one of those radon sealants work? In addition, we have an outside drain outside our house--should we do something about this? Should we do these things first,and then see about a venting system? What would the toatl cost be for something like this?
Also, and this is leeping me awake at night, how much damgage has this done already to our family in 2 1/2 months? I am really worried.
Sincerely, Catherine Galvin