Gear ratios, in the rear and in the transmission, change the ratio of revolutions of the axles/wheels vs engine RPMs.

Just as your car accelerates better in first gear than third, changing the rear ratio has the same effect. Rear ratios are determined by a lot of different factors, and changing the gears is not a job for a novice.

Putting a 3.73 or a 4.10 in your car will make it quicker. But, try riding around in 2nd gear for a few days. That is how it will behave in 3rd with the new gear set.