Recipes scale linearly. Divide all ingredients by 6 if the recipe is for a 6 gallon batch. the only exception will be the yeast.
If you are just starting out brewing though, I would recommend doing slightly larger batches. My guess is your equipment might be holding you back, but such a small batch size is going to be very fickle. You are going to need more precise measurements, and there will be a lot more room for error. Upping your batch size to maybe 2.5 gallons or so would help, and only slightly raise your cost. At least IME, hops and yeast are the most expensive ingredients, and I have never seen hops for sale for less than 1 oz increments, and you just have to buy a whole pack of yeast.