All usernames should be inside an array, let's call this array Users.
When searching for a name, you can loop through the entire array and check for usernames containing what you typed.
For example, if you typed dog, all usernames containing dog should pop up. dog282, somedog and doggy are examples that follow this condition. Note that hyperPad that have a built-in feature to check if a text contains something, so you will need to make your own.
So searching for dog should check for usernames in Users for keyword dog.
All results should be placed in an another array, let's call this Results. This is where all the desired usernames will be after a search.
After looping through Users, now you can loop through Results to get what you want to show. You can use Get Array Count to show the number of results or make a list appear.
I know you have a lot of questions on what to do, but I don't know which ones you're going to ask. Feel free to ask me any questions! π