Make sure the wheel brake isn't tightened down. If that's not the case, you need to determine if it's in the steering mechanism or the rudder itself. It would be best if you can disconnect the steering cables at the rudder quadrant - then it will be obvious which one is hard to turn. You can use you emergency tiller to turn the rudder (and it will be good practice if you've never used it). If it's in the wheel, suspect the wheel bearing, the sheaves or the chain/cable binding somewhere. If it's in the rudder, it's possible the shaft is bent or the bearings need grease/attention.