I would like to know how to adjust my scotts (made by John Deere) 1742 Lawn mower deck. It gives my lawn an uneven cut

Dirst double check your tire pressure, compare to manufacturers spec. Mine was cutting low on one side and it was tire pressure. If all four tires are at specs look for threaded rods that hand down from the frame to the deck. They usually have a removable pin and a threaded shaft that can be turned to raise/lower that side of the deck. Have the mower sitting on a flat hard surface and measure between the road surface and the blade tips, make both sides the same.