Hi munkyman welcome to the communities,
after you installed your first ESXi host, open a browser and go to https://your-ESXi-ip-or-FQDN
You can download the vSphere Client there. It's a windows application you can install on your desktop. It's often refered to as the "vSphere C# Client" in the communities and blog posts, as there is a new Web client implemented in the vCenter Server.
But for the start, install the Windows vSphere Client. You can then launch it and connect directly to your ESXi host. Here you can create your first VM, which can be the vCenter VM (Windows installation or Appliance, it's up to you).
After vCenter is running, you can either use the web client or connect to the vCenter Server with the vSphere C# client.
Tim