People staying at Disney-owned hotels can use the Magic Band to open the door to their hotel room, to get into the fitness center if their hotel has one, and at some hotels to show the cast members that they are entitled to use the pool. None of that applies to you.
People staying at a Disney-owned hotel can use the Magic Band to charge purchases in the parks and hotels because they are essentially using the Magic Band to charge to their hotel room; you can't do that because you are not staying in a Disney-owned hotel.
You need to make your Magic Band information is in your My Disney Experience account. If you got the Magic Band because you previously stayed in a Disney hotel, it should be in there. If you purchased the Magic Band, you need to enter the info.
You need to make sure your theme park pass info is in your My Disney Experience account. If you bought the pass online through Disney, it should be in there. If you bought it elsewhere, you need to enter the info.
After that is done: anybody can use their Magic Band to get into the parks.
Anybody can use their Magic Band to have Photopass photos saved to their My Disney Experience account. When you look at the photos in your My Disney Experience account, the photos will be watermarked unless you have an Annual Pass or paid for Memory Maker.
Anybody can use their Magic Band to tap the Fastpass tap points to get into the Fastpass lines.
Anybody can use their Magic Band to have ride photos saved to their My Disney Experience Account IF the Magic Band isn't too old. At some point (two years? three years?) the long-distance capabilities of the Magic Band die, even though the Magic Band can continue to be used for the things listed above.