Here is an overview of the Melodic Minor scale in the key of C, using the 7 Positions/Berklee System.
This is a variation of the William Leavitt/Berklee system from Modern Method for Guitar, as it was taught to me.
Practicing Scales and finding useful exercises
If you want to learn scales then you need to practice them in the right way. These posts will help you evaluate and improve how you work on scales in your practice routine
You can also download the chart as a pdf here: