Magic in the Marvel universe is the application of various forms of energy to manipulate various aspects of the universe beyond the scope of technology or science, using spells and phrases to simulate the powers of others, such as teleportation, astral projection, divination, mind control, Elemental attacks, and more.
There are various ways of gathering the energy needed to cast spells. Personal energies are those that a sorcerer can develop naturally and through studies of the mind, and they will get stronger over time, although without spells to extend one's lifespan, they will never reach the levels of the other two sources of energy. Secondly, you may tap into the ambient energy of the universe; however, spells cast while using this energy will be weaker as they are tied to the laws of the universe they are in. Lastly, you may use extradimensional energy; however, this is more dangerous than the other two sources as it comes with costs such as the entity you are borrowing the energy from deciding they don't like what you are doing, the energy corrupting you if gotten from an evil source, or any other consequences that would happen with borrowing energy from an entity or object.
There are various forms of magic schools, such as chronomancy, necromancy, chaos, chi, and significantly more than can be listed. This starts with MCU levels of power, but through training and time, it can reach comic book levels of strength. You instinctively know the basics and are able to master advanced techniques with ease. You know how to build basic tools like a Sling Ring as well. With enough time, you can achieve practically anything.
Take care when dealing with extradimensional eldritch beings when growing stronger, as you can very well doom a civilization by summoning a creature from the beyond in your covetous search for more power.