There are a few different ways that you can insert the user's name into a cell in Excel. One way is to use the USERNAME function. This function will return the name of the current user:

=USERNAME()

Another way to insert the user's name into a cell is to use the GetUserName function. This function will also return the name of the current user:

=GetUserName()

If you want to insert the user's name into a cell, but you don't want to use a function, you can use a macro. The following macro will insert the user's name into the active cell:

Sub InsertUserName()

    ActiveCell.Value = Environ("username")
    
End Sub