You need to get to the UW Campus, which is probably the easiest destination to find in Seattle (perhaps after the Space Needle). You can take any taxis or shuttles from the airport, they will know where to go.
On campus you need to get to McMahon Hall to check-in. Even if you are staying off campus, come here on July 17 at 6pm for our welcome reception.

In case you are driving, here are explicit directions:
Driving from Sea-Tac airport: Follow signs for I-5 Northbound, and then follow directions below for driving from the South.

Driving from the South: Take I-5 Northbound to the NE 45th Street exit (#169). Turn right onto NE 45th Street. Continue East about one quarter mile to 17th Avenue NE. Turn right onto the main campus. Stop at the gatehouse (Gate#2) and tell the traffic guide that you would like to go to McMahon.

Driving from the North: Take I-5 Southbound to the NE 45th Street exit (#169). Turn left onto NE 45th Street. Continue East about one quarter mile to 17th Avenue NE. Turn right onto the main campus. Stop at the gatehouse (Gate#2) and tell the traffic guide that you would like to go to McMahon.

Driving from the East: If you are on I-90, exit onto I-5 Northbound, and follow directions for driving from the South. Otherwise, use State Route 520; take the Montlake Boulevard exit. Continue North past Husky Stadium. Move over into the far left lane to prepare for the fork in road. When the road splits, take the left fork onto 25th Avenue NE. At the traffic light,turn left onto Pend Oreille Road. Proceed up the hill to Gate #3. Stop at the gatehouse for directions and a parking permit.

Here is a map of campus that includes the exit from I-5.
(Two pages, McMahon is on the second page.)

Parking fees are $4 each for Friday evening and Saturday morning (pay at the gatehouse on entry), free on Sunday. It is more expensive during the week. More information.