PO135 Code

Bad O2 Sensor. Sensor 1, Bank 1. Heater Circuit Malfunction. Where is this sensor located and how would I locate it? I assume from under the car, but I am not sure if I am looking for it on the front of the motor or the rear?

Is this a job that a normal do-it-yourself person should be able to handle? I would rather not have to disassemble alot of components to get to this sensor. Any suggestions or advise would be greatly appreciated. Thanks!