Park and Ramp wheels tend to be smaller and harder, but to get going just use what you have.
as you get better you can upgrade. Start out learning to "pump" and carve around the park, save dropping in till you get a little steadier.
Different surfaces can make a difference to what works best, but it is also down to personal choice
Hardness 92a to 101a harder wheels allow you to slide out of an bad landing and also get more speed.
size 55mm-62mm, small is better for tricks, larger good for speed and big air!