ASP.NET Application to update a column in in a table row by row in loop

Hi All,
I am very new to ASP.NET application development.
Can someone please help me out here.
I want to write an application in ASP.NET in which i want to update one column of the table for all the rows in table based on condition.
E.g:
Select * from customers 
Loop through all rows in customer table
Update Customer set address = 'abc' where customerid = '1'
end loop

Can someone please give the detail code and steps. Since I am a newbie is ASP.net more details will be great.

Thanks in advance