how can we call aspx.cs function on javascript

After getting your requirement the solution i think is that

1. you create a page on which you put the links.
2. by clicking that link you want to show a pop up to get the 'Name' of user, so i think you shoud create another .aspx page and on the click of link open the new page as a popup fill the required fields on that page and on the submit button send the 'user name' on the first page using query string.
3. on the first page you can check if there is some value in query string you can save it in database.