I need help getting a grants for start up

Start up of what?

I'm starting a new web store and selling god uses a mac stuff at macdivine.co.nr

Unless it is non-profit I doubt you will find a grant for that, better off trying to get loan for the start-up costs

I'm only in 7th grade

Then ask your parents for the money, you won't get a grant if your in 7th grade