I can manually write the code if I knew how to start a counter.
Counter and timer are NOT the same thing. You don't need either one, though.
Use the blink without delay philosophy. Turn the pin one. Record when that happens. Periodically (every pass through loop), see if it is time to turn it off (or back on). If so, do it, and record when that happened. When to perform the action will depend on what the action is (turn it off or turn it on) and what the "duty cycle" is.