Now, turn the tool in the other direction, and back it out of the roller

Now, turn the tool in the other direction, and back
it out of the roller. Set the tool to the side,
then work the chain very gently from side to side
and extract the inner side plates and roller.

Now is the time to re-route the chain through the
bike. You may want to have a chain retaining tool
or some to help you hold the chain in the right
spot as you route and repair it.

Now that the broken link has been removed and
you've re-routed the chain, you're ready to insert
a new link or simply connect the links that were
beside the broken one. The process here is the
same - align the two ends so that the link with
the inner side plates will fit inside the link
with the pin and outer side plates. Now, use the
chain tool to push the pin inward until it's
positioned evenly between the side plates.

The easiest way to learn how to do this or feel
comfortable doing it is to have someone show you,
then actually practice with a chain and a chain
tool. You'll have no trouble at all making a
temporary repair in a mountain bike chain once
you've seen it done by a professional and practiced
it yourself a few times.