For Connect & get Data using C# and SQL server

Question

I created a database in microsoft sql server, it has today, allSum columns. So I'm creating a C# program for update the DB. First of all allSum is 0. when i enter value in today column, I want to update allSum column. So we think now allSum value is 10, then when i add 5 for today column. i want to update allSum value is 15.

 

please can u help me.