What a nice gift!* Rosemary can be a difficult herb to grow indoors.* It prefers the soil to dry out a bit before watering, so stick your finger into the soil to the second knuckle.* If it's wet, don't water.* Keep it in a sunny window.* It doesn't mind cool temps.* It will grow outdoors in zone 8, so a light frost won't bother it.* Here's info about growing it outdoors.* What's important is that it comes from a Mediterranean climate where the summers are dry and the winters are mild.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.