What is sled event where a single athlete or doubles rest on a small sled and go down the track?

The sled event you're referring to is known as "luge." In luge, athletes lie on their backs on a small, one- or two-person sled and navigate a twisting, icy track at high speeds. The sport combines elements of speed, precision, and control, as competitors must expertly steer their sleds through curves and turns. Luge is a thrilling winter sport featured in the Winter Olympics and various international competitions.