First tampon questions?

Ok i'm 15 and just got my first period this week and it's really heavy and I was tired of changing pads so often, so I decided to use a tampon. The only ones I had at home were super. I got it in really easily, but now it fells uncomfortable when I sit down. I just put it in 10 minutes ago. Should I leave it in or what? Can I try and push it up further?