Save data from table control to Ztables

Hi Experts! I need some help with the Module pool concept.

In my case, I have an input field 'Material Doc. No.' based on which I'm getting 'Creation Date', 'Gate Pass Number', and a few other line items from standard table MSEG into the table control 'tbctrl'.
Also, In my table control, I've added a few fields from the custom table which should be input enabled. Once I give the input values in table control those corresponding values should be stored in custom table against the 'Material Doc No' 'Creation Date' and 'Gate pass Number'.
Please guide me where to write the logic and how it works.
I've tried some logic and it stores the data in Z tables as below:
Mat Do. CDate. GP Num. Tbctrl-f1 Tbctrl-f2 Tbctrl-f3

1001 19.2.20 7894 XXX YYY ZZZ

0000 00.00.00 000 PPP QQQ RRR

I also need to fill the 2 and so on rows with the header input fields.

Please do the needful.