What does it mean? "to the tune of a British drinking song"

Question

The next day, the commander of Fort McHenry printed and distributed the poem Key had written throughout Baltimore. That night, an actor sang the poem to the tune of a British drinking song. A few days later, the Baltimore newspaper printed the poem with directions that it be sung. 

Answer 1

شعر رو با ریتم یک آواز بریتانیایی خوند که موقع خوردن شراب می خونن.