Learn Spanish (Latin America): Mi tía vive en el norte.

You would use dónde, asking ¿Dónde vive tu tía? (Where does your aunt live?). We use dónde for a fixed location. You wouldn't use adónde (to where) because living somewhere doesn't involve travel or movement, and you wouldn't use de dónde (from where) because you aren't asking where she was born.

Why does the verb end in '-e' here (vive)?

Vive comes from the verb vivir (to live). Because mi tía (my aunt) is a 'she', we use the 'she' ending for this verb, which is -e. If you were saying 'I live', it would be vivo, and 'you live' would be vives.

Is norte a masculine or feminine word?

It is masculine! That is why it uses el, the masculine word for 'the'. In Spanish, compass directions like el norte (the north) and el sur (the south) are always masculine.

Why does tía have an accent mark on the 'i'?

The accent mark tells you to put the stress of your voice on the i. It also breaks the vowels into two separate syllables (TEE-ah). Without the accent, those two vowels would blend together into a single syllable.