How to fetch data in UI designer and update the records.

Hi,

I have a scenario wherein I want to update records once created when it is rejected by the approver. First I created and fill up the task when I submit it will go to the manager. When the manager login and rejects the task it will go back to the initiator and the initiator will update the fields required. I want to fetch the previous data and will allow the user to update his/her records then will submit again to the manager.

But my problem is I don't know how to fetch and update the record. How will I do it? I know how to fetch data but I dont know how will it be updated.

Please help. Thanks