how do I find Lanchpad and get it on my dock

It should by default be on your dock. Its the silver round disc icon with a rocket on it.

More details here: Use Launchpad on your Mac - Apple Support

If its not on the dock, then you can find it in the Applications folder in Finder.

You can Search Launchpad in Spotlight Search and drag the icon to your dock.

Should be part of the OS. Just have the dock open. Press Apple(Cloverleaf)+F together to find it. then when you have found it, click and drag it into the dock, or click on it, choose make alias, and drag the alias into the dock.

john b