Becoming legal?.....Soon? How do i go about it?

It's more complicated than that. Your aunt, once she is a citizen, can apply for a green card for your mother. However, if your mother is here illegally, it is not a straightforward process. Furthermore, depending on the country she's from, it's also a lengthy process. Sibling visas are NOT high priority and there's a wait of 10-12 years for some countries during which she may have to return to her home country. If you're in the 11th grade, it's also not too likely that you'd be able to get a green card before you age out. You'd best discuss this with an immigration lawyer.