Read only one row in data table

Question

I am writing a program with datatable to display this table.

In this table you can edit all columns, but I need this functionality included and only e.g. for 2 rows it is not possible to edit them.

when i try with

foreach (column System.Data.DataColumn in tab.Columns) column.ReadOnly = false; 

=> all table columns are not editable.

Thanks for any help.