How do I bind the local variable value(string) to the textbox in WPF MVVM project

private string _fileName;

public string FileName
{
    get { return _fileName; }
    set { SetProperty(ref _fileName, value); }
}

private void Browse()
{
    using (OpenFileDialog ofd = new OpenFileDialog())
    {
        ofd.DefaultExt = ".txt";
        ofd.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.";
        
        if (ofd.ShowDialog() == true)
        {
            FileName = ofd.FileName;
        }
    }
}

public abstract class ViewModelBase : INotifyPropertyChanged
{
    private static readonly ConcurrentDictionary<string, PropertyChangedEventArgs> EventArgsCache = new ConcurrentDictionary<string, PropertyChangedEventArgs>();
    
    public event PropertyChangedEventHandler PropertyChanged;
    
    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler is null) return;
        
        PropertyChangedEventArgs e = EventArgsCache.GetOrAdd(propertyName, n => new PropertyChangedEventArgs(n));
        handler(this, e);
    }
    
    protected void SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
    {
        if (Equals(storage, value)) return;
        
        storage = value;
        OnPropertyChanged(propertyName);
    }
}