The festivities actucally begin on Saturday, 4 June. I don't know why they don't include both days when advertising it. Anyway, on Saturday, there will be entertainment and the ever-present festival food booths.
On Sunday, the festivities begin at 9:45AM with the parade. The parade begins at the Max Valur supermarket that is at the west end of the one way shopping street (turn right at the first light outside the main gate and go up three traffic lights). From that point the parade will proceed down the one-way shopping street toward the base. At the traffic light at Sky Plaza, the parade will turn right and continue down to the Civic Center and Central Park (Train park). Here is a map of the route
The opening ceremonies take place at 10:45am at the Civic Center and the entertainment begins at 11am and runs through about 3:30pm outside the main gate at Sky Plaza and the Civic Center area.
The main gate will be closed to vehicle traffic from 5am Saturday through the end of the festivities. All vehicles must enter and exit the base via the Levitow and POL Gates.