My SQL Database records Update required

I have a MySQL database with some tables and data. I need to add some additional fields to my main table and then have a update routine that that can read the record in the table , get matching data from other tables and update the main table with calculations and the results to be written in the database table.

We can connect and share my screen to discuss further, I need this done immediately so must be done today.
If you cannot do it today please do not reply and waste time