How to change textbox value by selecting suggested value?

Question

Hello, Im creating a Desktop App in Visual Studio With C#.
I've a String array  called Tag_Word_Box.  In a textbox if I type something, then it will be show suggest words from Tag_Word_Box array.

In briefly, assume that- I've 5 words respectively [aabc] [abc] [abd] [abcg] [bcd] If I type in textbox only 'a' then it will be  show all of words without 'bcd'.
If I select 'aabc' or press enter one of suggesting words, then- it will be assign whole word in textbox, that means textbox value will be changed with selecting word by 'a'.

BTW, I know that- it will be solved by trie algorithm to find out words. But I want to know that how to do that operation in visual studio respect of C#  that-
1. to show suggesting words when I type something
2. and how do I change textbox value by selecting from those?

Thanks :)