This title, "The Charge of the Light Brigade," is pretty darn descriptive, and not much of a riddle. It tells us who the main characters are (the Light Brigade) and what they did (charge!). We imagine that when this poem was published, in 1854, most English readers would have been familiar with the basic events – this really was a "current events" kind of poem.
On the other hand, if you weren't born in the 1800s (and we're guessing you weren't), you probably don't now what a "Light Brigade" is. Here's a quick explanation: a "brigade" is group of soldiers. They're called "Light" to separate them from the "Heavy Brigade," another kind of cavalry unit at the time. Make sense? We just didn't want you to think they were actually glowing or anything. Still, there's a kind of lucky double meaning here, since the soldiers in this poem practically glow with a kind of holy goodness and courage.