"Add" Button Functions

Hi All Experts

 Currently i have a new ASP.Net form which has an ADD button next to a text box for user to enter.

The function of this button is to display an additional text box on the next row, upon clicking on it. This increment can go on for a long list as long the ADD button is click.

 

Appreciate if anyone could advise, or provide sample codings, on how to do it, thanks.

 
function Add_onclick() {
}
...