In Excel, you can create custom dialog boxes for user interaction within a macro using the Visual Basic Editor (VBE). Here's a general process:

1. Access the VBE:

- Press Alt + F11 to open the VBE.

2. Create a UserForm:

- Insert a new UserForm by going to Insert > UserForm.

3. Design the Dialog Box:

- Add controls like labels, text boxes, combo boxes, buttons, etc., from the toolbox on the left side of the VBE window.
- Position and size the controls using your mouse.
- Set properties of each control (e.g., font, caption) by right-clicking and selecting "Properties".

4. Add Code for Functionality (Event Procedures):

- Double-click on a control or the UserForm itself to open the code editor.
- Write VBA code to define what happens when a user interacts with the control (e.g., clicks a button, enters text).

Here are some key points to remember when coding:

- Use the `Show` method of the UserForm to display it in your macro.
- Access user input from controls using their properties (e.g., `TextBox1.Value`).
- Use conditional statements (If...Then...Else) and loops (For...Next) for complex logic.
- Close the UserForm using the `Unload Me` statement.

Here's a basic example:

```vba
' This macro displays a simple UserForm with a text box and a button.

Sub ShowUserInputDialog()

Dim userForm As Object
Set userForm = UserForm1 ' Assuming your UserForm is named UserForm1

' Set properties of the textbox and button controls (modify as needed)
userForm.TextBox1.Caption = "Enter your name:"
userForm.CommandButton1.Caption = "OK"

userForm.Show ' Display the UserForm

' Code to be executed after the user clicks the button can go here
' (e.g., display the entered name in a message box)

userForm.Unload ' Close the UserForm

End Sub
```

Remember: This is a simplified example. VBA offers extensive functionality for creating user-friendly and interactive dialog boxes for your Excel macros. For more advanced customization and functionalities, refer to VBA documentation or online resources.