Macbook access point compatability

I'm new to this forum and hope that someone will be able to help me.

I have an antenna that can potentially boost my wifi discovery to up to half a mile away, and I have a macbook pro. I was told that I needed an access point to link the antenna (and low loss microwave cable) to my macbook.

I bought an access point, which was not compatible to my Macbook, despite the helpful shop assistant telling me it would be, and neither radioshack or Office Depot seems to have an access point for my Mac.

I have the ADSL cable, male to male USB cable, and said antenna and cable, just looking for an access point to link this up.

I have a sailboat and want to be able to improve my chances of wifi reception whilst sailing and at anchor

Thanks in advance for any help forthcoming
Steve