Introduction
The most common fitting you'll find will be for a chainring to be attached to square taper cranks. If you want to replace the chainring, it's a much easier job if you first remove the drive side crank. Chainrings are connected to the crank via chianring bolts that require a special tool to tighten and loosen. You may want to replace a chainring because the teeth are worn, or because you want to adjust the gearing ratio.
This is a long guide, so you can choose to either watch the entire video above, or follow it in smaller chunks by clicking on the individual steps below.