GCSE results day doubts

I am an international student that moved to the uk in January. By the time I’d gotten here, most of the sixth forms had closed their applications. I’d already finished my gcse equivalent in the previous country I was living in and was midway through my alevels before moving here, therefore I already have my gcse grades. One school in my area had their form still open, and so I applied there and got in but I’m not quite sure of attending there. The other school websites mentioned that their forms would open again on gcse results day and that I could apply then, but this has left to totally confused. How am I supposed to apply for other schools but also get myself enrolled at the school I have an offer from at the same time? Please help. I can further clarify if my post doesn’t make much sense.

For the school you got an offer from on the 24th of August (results day) you need to resend your gcse result equivalent to the school the way they specified in the email stating your offer. It’s best to do this first hand on results day , then after you can apply to the other schools. This means that you have a secure place in the first school as even though you’re going to apply to the others they haven’t given you an offer so it’s not a definite spot. If you haven’t heard anything from the 2nd option schools it’s best to attend the initial offer school so that you’re not left withought nothing while you’re waiting to hear back as many schools are oversubscribed.
I really hope I helped let me know if something doesn’t make sense