This library is a layer on top of Friendly, so you must learn that first. But it is very easy to learn.

https://github.com/Codeer-Software/Friendly

Install Friendly.Windows from NuGet

PM> Install-Package Codeer.Friendly.Windows.NativeStandardControls

https://www.nuget.org/packages/Codeer.Friendly.Windows.NativeStandardControls/

Friendly.Windows.NativeStandardControls defines the following classes.
They can operate Win32/MFC control easily from a separate process.

• NativeButton
• NativeComboBox
• NativeDateTimePicker
• NativeEdit
• NativeIPAddress
• NativeListBox
• NativeListControl
• NativeMenuItem
• NativeMessageBox
• NativeMonthCalendar
• NativeProgress
• NativeScrollBar
• NativeSlider
• NativeSpinButton
• NativeTab
• NativeTree

//sample  
var process = Process.GetProcessesByName("NativeTarget")[0];  
using (var app = new WindowsAppFriend(process))  
{  
    var testDlg = WindowControl.FromZTop(app);

    //Button
    var button = new NativeButton(testDlg.IdentifyFromDialogId(1004));
    button.EmulateClick();

    //Edit
    var edit = new NativeEdit(testDlg.IdentifyFromDialogId(1020));
    edit.EmulateChangeText("abc");
    
    //Tree
    var tree = new NativeTree(testDlg.IdentifyFromDialogId(1041));
    tree.EmulateEdit(tree.Nodes[0], "new text"); 
}  

https://github.com/Codeer-Software/Friendly.Windows.NativeStandardControls/tree/master/Project/Test

For other GUI types, use the following libraries:

• For WPF.
  https://www.nuget.org/packages/RM.Friendly.WPFStandardControls/

• For WinForms.
  https://www.nuget.org/packages/Ong.Friendly.FormsStandardControls/

• For getting the target window.
  https://www.nuget.org/packages/Codeer.Friendly.Windows.Grasp/