He's not too old. I don't know that dogs are ever too old to learn. They seem to thrive on learning and love being praised and rewarded when they do well. Basic commands like sit, stay, come are easy to train. There are lots of videos on youtube about training, some better than others. I use voice commands along with hand signals. Decide what words/signals you want to use ahead of time & be consistent, and praise, praise, praise & a treat
