Script to copy record contents to overwrite linked record in another table

I have two tables:

  1. Member Profile
  2. Update Profile

Members can submit updates to their profile using a form that goes to the Update Profile table. They pick the member to update when they submit the form, linking the two records.

I then review the updates and would like to click a button that runs a script copying the details from Update Profile to overwrite the linked record in Member Profile.

Can someone help point me in the right direction for how to script this?
I’m particularly lost as to how to read the contents of a specific cell from the current record.

Thanks!