Is everything pre-dertermined? If yes, what is our part in going to jannat? If Allah knows evrything. that means it has happened right?

Taqdeer refers to the absolute knowledge of Allah Ta’ala of everything even
prior to its existence. Since the knowledge of Allah Ta’ala is perfect,
everything will take place exactly according to his knowledge, but in the
case of our deeds it is through the choice of every individual.

A person should adopt the means to do something. Thereafter, after the
action has been done, the belief of Taqdeer comes in that everything
happened through the will of Allah Ta’ala. In one Hadith, Nabi (Sallallaahu
Alayhi Wasallam) said, ‘Allah Ta’ala has already written the abode of every
single person in Jahannam or Jannah. The Sahaaba (Radhiallaahu Anhum) asked,
‘O Nabi (Sallallaahu Alayhi Wasallam), should we not put our trust on our
books, i.e. what has already been determined for us and leave out doing
actions. Nabi (Sallallaahu Alayhi Wasallam) replied, ‘Carry on doing
actions. Everything will be made easy for what it has been created for.’

and Allah Ta’ala Knows Best

Mufti Ebrahim Desai