Tracing a darknet lead on Bitcoin Cash means following spent outputs from one transaction to the next. Start from the address you were given and list the transactions that funded it. Then follow each output it created until the trail ends at an unspent output.
Following the flow
Every input points to a prior output, so the chain of references is the trail. The transactions are pseudonymous, which means an address alone names nobody. Keep the note to what the ledger shows and leave marketplace names out unless your own evidence supplies them.
Filing the trace
Write down the address, the transaction count and the totals received and sent from the free check. The check reports block heights instead of dates, so order the hops by height. Stop the trace where the evidence stops.