Route

There are a number of routes, depending on what you want to see, whether you are in a hurry, or want to take side trips.  The most direct route though NV is U.S.95 & U.S.95 Alt. to Fernley, then cut across 0n I-80 to Reno and take 395 north until you get to the turn off for Klamath Falls.  Check Google Maps for routing.  There are a lot of things to see on the way.

Slightly quicker, and less interesting way would be to take US95 north through Las Vega. More interesting, and probably more traffic would be to take I-10 west, then I-5 North. You could also go all the way west to highway 101, but the more important thing is what the goal is. Plan on three or four days regardless.