The PA28 has (or rather: should have) a tow bar that ends in a very broad U-shape, with downturned ends. These downturned ends go in the two holes left and right of the nosewheel strut. Sometimes there's a locking mechanism on the towbar as well.
You can then steer the nosewheel with the towbar, and use the prop to pull/push the aircraft where you want it to go. Don't force the nosewheel into a tight turn though; I think about 30 degrees either side of center is the maximum that the steering assembly can handle without damage.
Best practice is to always pull/push at the root of the prop blades, not at the tips or in the middle. Make sure the prop is set in a horizontal position first, and before you touch the prop, look in the cockpit to ensure mixture is set to idle, and the magnetos are off.
And the other bit of generic advice is to take it slow. Walk to the wingtips to see, if you're not 100% sure if they clear an obstacle. Get help if you find you can't do/see it alone. There's been too much damage from pilots wanting to get an airplane out of, or into a hangar just a little bit too fast.
In fact, the insurance at my club has a deductible that's 10 times higher when taxiing or ground maneuvering an aircraft, compared to flying incidents/accidents. Ouch.
(And take care not to fall backwards or forwards when the towbar suddenly slips out of the holes, and take care when the ground is slippery. Ask me how I know...)