Depending on the plane, and the surface you fly off of, you can get by with out a stearable tail wheel. You can actually taxi that way too, but it takes more effort.

To turn a tail dragger that has a skid or fixed wheel, you often have to use bursts of throttle coupled with down elevator and lots of rudder. The prop blast hits the elevator and rudder, lifting the tail off the ground, and swings the tail around. Getting good at it so you can actually point the plane where you want takes time though.

Some planes are light enough on the tail (CG location vs main wheel location is what matters here), and have enough rudder in the prop blast that they actually do taxi around normally, even with out a stearing tail wheel. But these planes are also prone to flipping up on the nose if you hit a bump, since the CG has to be very close to right above the gear.

Your life will be much easier with a stearable wheel. It's usually worth doing.