Karky - It's called Battlestar Galactica, so your best bet is to know what BSG eps your looking for.
Here is the show site:
This series began with a 3 hour "pilot" before the first season. It's crucial to see that before watching Season 1. First episode of season 1 is called "33." There are currently three complete seasons of the show. There is also a 2 hour movie called "Razor" that is considered the start of Season 4 (though it chronologically happened earlier in the series).
Right now, the show is on hiatus. It wasn't supposed to start airing new eps until winter at the earliest, but with the writer's strike, this is even more complicated. There has also been talk that NBC will use this as on network programming, if the strike lingers. This might push season 4 airing even further behind, because then nothing new would come out until the rest of the show airs.
As for getting the eps, the first two seasons are out on DVDs. There are also other ways of finding these things. Hehe.
My recommendation: Follow the episode list & start from the beginning and do NOT let anyone spoil you. Don't try to read too much about the show now, or you will see all sorts of info that will make it slightly less enjoyable. The show still rocks, though!