How to create a search by text box in C#

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C#

UWP

I have to create a list of students and I need to create a search bar using text box. The student details are in {studentABC}. I need to filter the students by first name and display in a list.

It's not working. What am I doing wrong?

What I have tried:

<TextBox x:Name="search_box" Margin="60,20,0,0" 
            RelativePanel.AlignBottomWithPanel="True"
            PlaceholderText="Search first Name"
            Height="40"
            Width="200" TextChanged="search_box_TextChanged">

the first name code is

<ListView.ItemTemplate >
   <DataTemplate x:DataType="local:studentitem" x:DefaultBindMode="TwoWay" >
      <StackPanel Orientation="Horizontal" >
         <TextBlock x:Name="fname" 
                       RelativePanel.AlignVerticalCenterWithPanel="True" 
                       RelativePanel.AlignTopWithPanel="True"
                       Width="150" Text="{Binding FirstName}"  
                       Foreground="Gray" FontSize="16"
                       Margin="20,0,10,0" />

my data ascess

public static List<StudentItem> getallstudent(Int64 Id)
//etc code..!
	SqliteDataReader query = selectCommand.ExecuteReader();
    while (query.Read())
    {
        var e_item = new studentitem();

        e_item.ID = query.GetInt64(1);
        e_item.FirstName = query.GetString(2);
        e_item.LastName = query.GetString(3);
        e_item.DOB = query.GetString(4);
		 studentABC.Add(e_item);