I'll also say if you want to celebrate Pete Seeger, or learn more about him, watch the documentary Wasn't That a Time, an utterly joyful, life-affirming film about a reunion of The Weavers in the 1980s. Or track down the American Masters production that PBS did a few years ago.
Other than that, I'll just post a video of Pete Seeger singing one of his renowned songs. That explains most of it anyway. So, here he is singing with his grandson, Tao Rodriguez-Seeger. (And if you look closely, on the left with long hair and playing guitar, that's Arlo Guthrie.) And getting the audience to sing along.