html text on text change event run c# code

See more:

C#

ASP.NET

HTML

hi all
my project is online shop
and when i display on cart page i get product name and quantity requested
so the quantity display in textbox
i try to add event to textbox , when i change qty value i will run some c# code
this is some code i used to generate mt textbox
html.Append("<input type='text' name='Quantity' value='" + row["QTY"] + "'>");

how can i add event to run method in c# code ?
please help :)