I am 17 years old and I can't get my forskin over the tip when it's soft and it's even harder when it's hard so what do I do
Stretch your foreskin - NOW. This is common until around 16 or so.
Get an erection and pull down on the shaft skin so the glans (head) spreads the opening. You can also use your fingers. Do it as often as you can. It will help to do it in the shower, the warm water helps soften the skin. The more you do it the sooner you'll notice results.
Your foreskin should easily slide up and down over the glans when erect.
Normal erections and masturbation will help too.