Rhythm is very much about "feel." Kyle, baz, and Steve have all given good advice. One bit I'll add...don't worry about getting it "stroke-for-stroke" perfect. Make the song yours! You need to pick rhythms and strums that set the mood of the piece, but it doesn't have to be exactly the same as someone else does it. Also, when you are listening to recordings there are often a number of instruments working together to set the mood - you can never do what all those instruments are doing...so pick the parts that move you and try to get that feel on the uke.
John