Welcome to the site as well, I would suggest if you are new to magic(k) to read more about magic(k)...This means books or trustful reasearch. As you will see magic(k) isn't what is portrayed on "Harry Potter", "Lord of the Rings", and or "Warlock"...ect there are many more.
Magic(k) can not change your physical body. There are laws that prevent us, no one can go beyond these laws, as they are the "Laws of Nature." and the "Laws of the Universe". They are the line that separates fantasy from real.
Most people come onto this site say "Black" and "White" as labels for magic(k), as it's your opinion, most people use the labels "Negative" and "Positive" this is because "Negative" can do good as well as bad. "Positive" can also do evil as well as good. So on so forth.
Starting Spell casting- Well before "Spell Casting" you should read up as much as you can (again a reliable source). Remember the basics that are found on this site are not necessary, but they do help getting you started and understanding the basics of magic(k).
Emotions- Emotions are a kind of big part of magic(k) and "Spell Casting". They help focus your intent in magic(k).