How do you bind and handle events?

You can bind events to DOM elements started with the on<event> with a delegate-type value. The attribute’s name always starts with “on.” In the following code example, the “UpdateHeading” event is triggered when the button is clicked.

<button class="btn   btn-primary" @onclick="@UpdateHeading">
       Update heading
   </button>
    

 @code {
       private void UpdateHeading(MouseEventArgs e)
       {
           ...
       }
   }  

I would suggest you check the below link for better understanding:
https://docs.microsoft.com/en-in/aspnet/core/blazor/components?view=aspnetcore-3.0#event-handling