Take the MSF dirt bike school, both of you. Theyll teach you on 250s, then take what you learned and ride, ride, ride. Dont do anything your not comfortable with. That being said you only get better by going outside of your comfort zone, just do it gradually.
Learn the basics like speed is your friend, how to stop, how and when to use which brake, etc...get comfortable loosing traction, one of the best skills to learn is locking the rear tire, get used to the feeling now. Stuff like that, find a good coach.
March is the noob rally in death valley, if youre up to it attend.
You cant fix stupid, but you can sedate it.