You will have to give a bit more info about the boat like length and weight and maybe model.
As a general answer:
the trailer has to be for the length of the boat and must have sufficient weight capacity (boat + trailer weight). You can then chose between a roller or a bunk trailer and you have to set up rollers/bunks to support the boat at the correct location.
Last but not least you have to move the boat back and forth on the trailer until you have the correct tongue weight. North American trailers (single axle) are designed to require 8-10% tongue weight to be stable.
There are pro's and con's with both styles of trailers. Some will only go roller and some bunk.......
