I've trod these steps from day to day I've slid down both her railings I've pelted snow down Junior's necks Oh yes, I had my failings
I've flirted on the old stone seats Like kids since Earth's Creation Yet with regret I leave these steps To the rising generation.
A graduating student looks back over his school years, using the front steps as a way into all his memories. He remembers sliding down the railings, throwing snow at the younger boys, and flirting with classmates on the stone seats. The speaker doesn't take himself too seriously: "Oh yes, I had my failings" is a cheerful shrug, as if admitting to a bit of harmless mischief.
The mood is light and teasing, but there's a gentler feeling underneath. The line about kids flirting on those seats "since Earth's Creation" is a joke, though it also suggests that what he did isn't special to him alone. Every generation has done the same, and every generation has to leave. That's where the tone shifts. "With regret" is the only openly sad phrase in the poem, and it arrives right at the end, as he hands the steps over to "the rising generation." The humor softens the goodbye without hiding it.