what do I do once I’ve received an offer from a sixth form?

I just received an email and an offer from one of the schools I’ve applied to for sixth form, what are the next steps? Do I accept the offer or do I only accept after results day. I have other sixth forms that I’ve applied to aswell

Does the email not say what to do if you want to accept the offer? Do you want to accept the offer?

I reread the email, and they said that i have to respond to the offer by the 28th March or my offer may be withdrawn. my question is that if i accept the offer for this school would I still be able to accept offers from others schools before GCSE’s? Or am i only allowed to accept one