This is a basic outline:
1. Cardio: 4 to 6 days per week, moderate, hard, easy intensities with days off for recovery.
2. Strength: strength for your lower body, muscle endurance for your upper body and a combination for your core. 2 to 3 days per week depending on the time of the year.
3. Nutrition and hydration: balanced meals and snacks throughout the day, hydration with water or sports drink when hot and humid.
4. Practice on the MX bike: 2 to 4 days per week with racing on the weekend. Recovery day on day immediately following race. Quality not quantity practice.
You should subscribe to Amateur Motocross Magazine, I have been doing articles on training that should help you.
Alan G. MXT