In Mirror, Network Manager Callbacks not recognised by editor

Hi. I am using Mirror and I want to use certain Network Manager callbacks. The problem is that when I type the name of a callback, the name is not recognised. My class derives from Network Behaviour, and my guess is that it needs to derive from something else in order to implement a Network Manager callback - if so, what does my class need to derive from?

edit:
After some trial and error, I see that there are multiple other things wrong with the way I’m declaring the OnStartClient() callback. Could someone kindly give me an actual example of how I would declare a Network Manager callback, because I the information from Mirror here doesn’t go into that

Create a new network manager class that extends the NetworkManager class, then override the methods you’re interested in.

public class NewNetworkManager : NetworkManager
{
    public override void OnStartClient()
    {
        // your code here
    }
}

There’s actually a template for it under Create->Mirror

Thank you, I understand now