The Fairfax County Firefighter's Canteen, an all-volunteer nonprofit group that provides refreshments to professional and volunteer firefighters and rescue personnel in Fairfax County during prolonged incidents, and the Fairfax County Retired Firefighters Association will be the beneficiaries of a "Blazing Bluegrass" concert on Saturday night featuring three bands. The fund-raiser will take place from 7 to 11 p.m. at Robinson High School, 5035 Sideburn Rd., Fairfax

Tickets are $10 per person, with children under 10 free when accompanied by an adult. They may be purchased at any Desperado's store in the Washington area and at the Music Store on Chapel Road in Clifton.

For more information, call Pamela Weiger, public information officer, Fairfax County Fire and Rescue Department, at 691-4385 or 691-2126. The Fairfax County Chapter of the American Red Cross has a pressing need for volunteers who are able to teach Comprehensive Infant Care, Babysitting, and Kids in Safety Seats courses. Training will be provided.

Volunteers are also needed to work at Yesterday's Rose, a resale shop on Little River Turnpike.

Experienced volunteers interested in computer programming, data entry and systems are being sought. Flexible hours and benefits are available. Call the Office of Volunteers at 591-8091 for further information or to volunteer your services. Grab your tennis shoes and join the Alexandria Department of Recreation and Cultural Activities for an evening of co-ed wallyball, a game of modified volleyball that is played inside a racquetball court across a net with teams of five to eight people. A potluck supper is planned for after the game on Friday, June 27, from 7 to 10 p.m. at the Chinquapin Park Recreation Center. Participants are asked to bring a main dish, salad or dessert and their favorite nonalcoholic beverage. Beginner and Olympic-caliber athletes are welcome for this activity. For registration information, call Terrie Kolodziej at 931-1127. SPECTRUM, the United States Air Force Band, will perform an hour of light rock music as part of the 1986 Music at Twilight concert series held annually at Fort Ward Park. The concert will take place at 7:30 tonight in the Fort Ward Park Amphitheatre, 4301 W. Braddock Road, Alexandria. In the event of inclement weather, the concert will be canceled. For more information, call 838-4843. A few spaces are still available for 10- to 12-year-olds in the Ramsay Nature Center's summer day camp. The program offers adventure training, during which campers learn basic concepts about nature through firsthand experience. The camp will be led by two naturalists and a volunteer counselor, and will meet from 9 a.m. to noon, July 21 through 25.

A $46 tuition fee covers the cost of a camp T-shirt and an overnight camping trip. The Ramsey Nature Center is at 5700 Sanger Ave. in west Alexandria. For further information or registration forms, call Gale Kobray at 838-4829.