WPF C# Command Binding - wpf

Question

I have problem with binding, I want to navigate to new Page (not new window). I Have tried by click event, this is working but if I am trying by ICommand interface, it isn't working good. I don't want why, i have tried in cross-platform, everything works fine. I am thinking what's is wrong with that code.
Main XAML
<Window x:Class="WpfAppFP.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WpfAppFP"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525"
Background="#67696d"
x:Name="_CLK">
<Window.Content>
<Border Background="#202021" CornerRadius="40" >
<StackPanel Margin="20">
<Label Content="Type in your data" Foreground="White" HorizontalAlignment="Center" FontSize="20" FontWeight="Bold"/>
<Separator/>
<Label Content="Name" HorizontalAlignment="Center" Foreground="White" FontWeight="Bold"/>
<TextBox HorizontalAlignment="Center" MinWidth="320" MinHeight="32" Foreground="Black" Background="#f5ddff" FontSize="15" FontWeight="DemiBold"/>
<Label Content="Surname" HorizontalAlignment="Center" Foreground="White" FontWeight="Bold"/>
<TextBox HorizontalAlignment="Center" MinWidth="320" MinHeight="32" Foreground="Black" Background="#f5ddff" FontSize="15" FontWeight="DemiBold"/>
<Label Content="Social" HorizontalAlignment="Center" Foreground="White" FontWeight="Bold"/>
<TextBox HorizontalAlignment="Center" MinWidth="320" MinHeight="32" Foreground="Black" Background="#f5ddff" FontSize="15" FontWeight="DemiBold" MaxLength="11" />
<Separator Margin="0,10,0,0"/>
<Button HorizontalAlignment="Center" MinHeight="32" MinWidth="120" Foreground="Black" Background="White" Margin="0,10,0,0" Content="Login" FontWeight="Bold" BorderThickness="2"
x:Name="BtnClk" Command="{Binding CandidatesVM}"/>
</StackPanel>
</Border>
</Window.Content>
MainPage
public partial class MainWindow : Window
{
CandidatesVM candidatesVM;
public MainWindow()
{
InitializeComponent();
candidatesVM = new CandidatesVM();
this.DataContext = candidatesVM;
}
}
CandidatesVM
public class CandidatesVM
{
public NavigationCandidates navigationCandidates { get; set; }
public CandidatesVM()
{
navigationCandidates = new NavigationCandidates(this);
}
public void Navigate()
{
MainWindow mainWindow = new MainWindow();
mainWindow._CLK.Content = new Candidates();
}
}
NavigationCandidates
public class NavigationCandidates : ICommand
{
public CandidatesVM candidatesVM { get; set; }
public event EventHandler CanExecuteChanged;
public NavigationCandidates(CandidatesVM canVM)
{
candidatesVM = canVM;
}
public bool CanExecute(object parameter)
{
return true;
}
public void Execute(object parameter)
{
candidatesVM.Navigate();
}
}

Answer 1

Bind to navigationCandidates, that's the command:
<Button x:Name="BtnClk" ... Command="{Binding navigationCandidates}"/>
Then I don't know why you are creating a new instance of the MainWindow in the Navigate() method of CandidatesVM. I guess you want to set the Content of the already existing one:
public class CandidatesVM
{
public NavigationCandidates navigationCandidates { get; set; }
private readonly MainWindow _mainWindow;
public CandidatesVM(MainWindow mainWindow)
{
_mainWindow = mainWindow;
navigationCandidates = new NavigationCandidates(this);
}
public void Navigate()
{
_mainWindow.Content = new Candidates();
}
}
public partial class MainWindow : Window
{
CandidatesVM candidatesVM;
public MainWindow()
{
InitializeComponent();
candidatesVM = new CandidatesVM(this);
this.DataContext = candidatesVM;
}
}

Answer 2

You should be binding to navigationCandidates rather than CandidateVM
<Button HorizontalAlignment="Center" MinHeight="32" MinWidth="120" Foreground="Black" Background="White" Margin="0,10,0,0" Content="Login" FontWeight="Bold" BorderThickness="2"
x:Name="BtnClk" Command="{Binding navigationCandidates }"/>
Why ? CandidateVM is served as a data context to your window. So you should be binding to some property of data context and not to data context itself.