I have a hunter fan I purchased three speed switch. The fan wires are yellow white black and gray how should they be place into positions 1, 2, 3, L, aine the previous switch was a one speed?/

First, make sure you have the correct switch. Second, how was the old switch wired?

See:

Ceiling fan pullchain replacement and repair - Ceiling Fans N More (http://www.ceiling-fans-n-more.com/ceiling-fan-pullchain-replacement-and-repair.php)