How do you put a chain on a bike with gears?

To put a chain on a bike with gears, first shift the gears to the smallest chainring and smallest cog. Then, loop the chain around the chainring and the cog, making sure it is properly aligned. Next, thread the chain through the derailleur and connect the ends using the master link or chain tool. Finally, test the chain by pedaling to ensure it runs smoothly through the gears.