Off of I-95 SOUTH, about 15 miles south of I-495, look for signs for DALE CITY, exit number 156.  Go in the direction of VA-784 EAST or RIPPON LANDING/NORTHERN VIRGINIA COMMUNITY COLLEGE.

Follow the signs to Leesylvania State Park.  They are large and easy to follow.  (They will have you turn RIGHT on VA 638 which you follow for about 1.5 miles to Rt. 1, Jefferson Davis Highway; turn RIGHT and then make the first LEFT onto NEABSCO RD.)

Now go about 1.5 miles and turn right at the sign for the entrance road into Leesylvania State Park.  Go to the end of the road to the second parking lot on the right, which is where the Lightnings will park and set up.

You don't really need them, but if you'd like to get an internet map, use the park's address:

16236 Neabsco Road
Woodbridge, VA 22191

Maps and directions are available from local.google.com. The map produced stars the entrance to the park at the point where Neabsco Creek Road takes a right turn south into the park entrance..

Finally, here is a park guide (map) that shows the inside of the park.  Notice that once inside the park, you follow the road all the way south, pass underneath the railroad tracks and go north again to get to the sailing area.