I have a Kenmore 90 series washer and it is not spinning. ?

The washer is filling with water and draining but is not spinning or agitating when it is suppose to. I can hear a grinding sound coming from inside the unit as if there is something spinning inside of it but the drum is not. Do you have any suggestions as to how I can fix this? I am pretty mechanically incline and have not taken it apart yet because it has just happened. Just giving you that info because I feel as if I am able to fix it myself.
Thanks