But first, let me take a selfie. (Photo by Noel Vasquez/Getty Images)

I’d never heard of one of the acts for the Nationals’ free postgame concert series that was announced Thursday, which suggests I’m less knowledgeable about popular music than Dan is about popular movies. Or maybe not. Austin Mahone anyone?

Anyway, here’s a two-minute guide to the non-Opera performers coming to Nationals Park this summer.

Plain White T’s — Thursday, June 5

You might know this group of high school friends for their platinum hit “Hey There Delilah.” They’re releasing another album, “American Nights,” later this year.

Sports Connection: The Chicago natives performed at the NHL Stadium Series game between the Blackhawks and Penguins in March. Bassist Dave Tirio is a die-hard Cubs fan.

Best Walk-Up Song: “Serious Mistake,” but only for situations when the pitcher intentionally walks the preceding batter.

Austin Mahone — Saturday, July 19

All … no, more than you need to know about the 18-year-old Mahone, who won an MTV VMA for “Artist to Watch,” is that his dedicated fans are known as the Mahomies. Which makes me think of Paul Maholm.

Sports Connection: The San Antonio native says he’s a Spurs fan, though he wore a Bulls jersey and hat on his first single cover. Lest you accuse him of being a bandwagon fan, know that he was 3 when Chicago won its last NBA title. Dang. Also, BALL IS LIFE.

Best Walk-Up Song: “Banga Banga.” You know, for a rookie, in lieu of having him carry gear or wear a silly outfit.

Martina McBride — Saturday, Aug. 16

The most accomplished act of the bunch. According to the Nationals’ release, McBride has “14 Gold Records, nine Platinum honors, three Double Platinum Records and two Triple Platinum awards.” Her new album “Everlasting” debuted at No. 1 on Billboard’s country albums chart.

Sports Connection: Dale Earnhardt Jr. asked McBride for an autograph after she sang the national anthem at Talladega in 2000. He went on to win the race with McBride’s autograph in his car as a lucky charm.

Best Walk-Up Song: “This One’s for the Girls.” The only McBride song I know. Kinda catchy.

Last year’s lineup featured Blues Traveler, Thompson Square, Gavin Degraw and Montgomery Gentry. Dierks Bentley, the Wallflowers and Third Eye Blind appeared in 2012. I’ve never been to one of these postgame concerts. Are they fun? Should I check out Mahone?