Retrieving list of data in TextBox in asp.net webform

i am working on this project, its backoffice data entry project, here in this checker module client can check what he enter in maker module, and my problem is i want bank list in textbox with select button, and after i select one data, example bank name: state bank of india, i can edit it also. (sorry for bad english) plz help. i have no idea about it i am a student.

https://i.stack.imgur.com/wGRTR.jpg

https://i.stack.imgur.com/YFofk.jpg