Firstly, I am sorry for some of the shitty replies you have had on this question. People suck, especially when they feel brave behind their keyboard.
Have a look at the clothing you are wearing. Synthetic fabrics like polyester will make you sweat more, whereas cotton is more breathable. Also have a look at how tight your clothes are under the arms; I have certain t-shirts that are really tight under the arms and I sweat more when I wear those.
Do you shave your under-arms? I ask because this is something that can make a difference person to person. For example, I find that I sweat less when I have a bit of pit stubble. I know that sounds counter-intuitive, but if I have no hair there at all, I get sweatier. Experiment with this and see what works better for you.
Shower well every morning if you can, and try to wear a new shirt every day, making sure you wash your clothes after wearing.
Product-wise, I don't know if you're from the UK or elsewhere, but as I'm seeing this question on Yahoo UK, I'll answer for that.
You can get deodorant sticks from both Dove and Sure which I think are called something like "maximum protection". They are literally the exact same from both brands, but different scents I think.
They look like a normal dry-stick but they're a bit bulkier, and what happens is you twist the bottom and the product comes up through some holes in a cream-type consistency. Use it like a normal dry-stick and let it dry before getting dressed. Be cautious with usage though, it's hard to tell when it's going to run out. Always have a backup.
I used to sweat a lot as a teenager and those minimised my issues. I would also put some antiperspirant spray on top if I felt extra self-conscious - Sanex sprays are great, especially the purple one, as are the Superdrug own-brand ones.
I would also keep wipes and a deodorant in my bag to top-up when I felt I needed it too – I would just go to the bathroom, take a baby wipe and go over my underarm a bit with it, let it dry then re-apply my anti-perspirant.
Just be careful not to clog your skin up too much.
Most importantly, please remember this is normal and it will most likely get better. I had this when I was like 14-17 and then it went away, these days one quick spray under each arm after my shower and I'm good until I go to bed in the evening. Your hormones are just going crazy at the moment.