We recommend always replacing your sprockets at the same time as replacing your chain as a new chain on worn sprockets will shorten the lifespan of the chain. The first step to installing a new chain is to adjust your rear wheel chain tensioning blocks as far in as possible. This will allow plenty of room to tension your chain as it wears and stretched, just leave the axel loose while you are working out the chain length as it will help working it out. Unravel the chain and roll it out around the sprockets on the bike as you would apply any chain which is cut to length. Once you have the chain unraveled you will notice an overlap where the chain is to join.
Visit our helpful guide on "when to replace your dirt bike chain" here.