4, 5, and 6 string banjos all have differnt playing styles -- none is "easier" in my opinion -- they're just different. Your 6-string can be tuned and played like a guitar. Use a guitar instruction book to get started. The 5-string is the banjo most commonly played today and most commonly associated with folk music, blue grass and old-timey. There are lots of instruction books out there. My favorite, because its the one I started with, is Pete Seger's How to Play the 5-String Banjo. You don't need to read music to learn from it. The 4-string was popular back in the early 20th century for jazz, ragtime, and such. Today, it is used frequently in Irish music. Listen to Mick Maloney -- he's terrific on the 4-string.

And beware -- you buy one and get hooked, you're likely to buy another...and another...and so on.

And remember the old Appalachian saying: "Do you know how to read music?" "Not enought to hurt my playing." ;-)