How do I inform the police my neighbor is dealing?

I live in an apartment complex, recently, the kids across the hall got arrested (for drug chargers) and were evicted. Low and behold, a few weeks later some new people moved in (a guy and a girl), shortly after they moved in the odd behavior started. People stopping by their apartment at all hours of the day and night and staying for only a few minutes. Every time they open their door and im in the hall, the smell of marijuana rolls out. I'm not saying people who smoke weed are bad, believe me I did it in college and high school. But I'm sick of hearing the drug talk in the halls ( people constantly standing at their door saying stuff like "come on boi, lemme get a dime") im sick of it. i know their selling. I live in high point, north carolina. How do I go about informing the police and getting them to act on this?