Now that you have a working cluster connected to your Kubernetic client you can continue with handling the namespaces.
Namespaces is a way to virtually split an existing cluster to separate environments. Most objects inside Kubernetes act inside a specific namespace, which means when you switch namespace a fresh environment will be provided.
Go to screen Settings > Namespaces
You will see there your existing namespaces. Kubernetes creates an active "default" namespace automatically which is where your objects act on by default. It also creates a "kube-system" namespace where all cluster's management objects are stored (e.g. A DNS service).
Deletion of a namespace propagates the deletion of all resources under that namespace.