how to lock excle file cells in C#

Question

Hello friends,

right now i m facing a very big problem.. actually i have export data into excel from data grid view.. its done perfectly .. but i want to lock cells like first column and second column of Excel file.. and also validate locked cells.. only enter numeric value or decimal and it can not be greater then max values.. so hope u understand what i want.. if you have any solution regarding for this issues the reply me ASAP..

thanks in Advance