Employees first
Payroll → Manage employees → New employee. Payroll cannot run without them, and the page says so rather than showing an empty screen.
Each record holds how they are paid, their rate, and the details the pay run needs.
A pay run
New run. Choose the period, check what each person is owed, and post it. It writes the journal entries: wages to expense, and what is withheld to the liability accounts that hold it until it is paid over.
Hours from the time clock
If people clock in and out, their hours flow into the run instead of being typed. Hours allocated to a project also land in that project's cost.
Who can see it
Payroll is restricted by role. If you cannot open it, somebody with an owner or admin role has to give you access — and Runny cannot read payroll either, deliberately.