The will usually be a lever on the handle of the lawnmower or on the body of the engine. Put the throttle lever in a mid-to-high position. The choke helps provide a richer fuel-air mixture to the engine, which helps it stay running until it warms up. Once the mower has been running for a few minutes turn off the choke.
What does a choke do in an electrical circuit?
In electronics, a choke is an inductor used to block higher-frequency alternating current (AC) in an electrical circuit, while passing lower-frequency or direct current (DC). The name comes from blocking—"choking"—high frequencies while passing low frequencies.