Can you help give me some tips for improving my running speed when I do running workouts?

I go to the ymca almost everyday to run or do the elliptical. When I get on the treadmill I set it on an incline and set the speed between 6miles and 7miles an hour. I also every couple of minutes change the incline so I don’t get bored. I try to do this for at least 30 minutes so I get 3 miles in . My goal though is to be able to do 5miles in 45minutes or 6 miles in under an hour which just seems so hard. I’m not lazy though because I can definitely do the 3miles.Ihope to be able to run 5 k’s and 10k’s. So can anybody help me so that I could get there faster and make some progress? Thank you.