Kubernetes rolling update using helm

I am new to Helm. I have installed Minikube & Helm on my windows system. I am able create pods using Helm and see deployment,pods & replicaset in dashboard.

I want to do rolling update using Helm. Guide me how to do rolling update in K8s using Helm.

Creating Tomcat pod using Helm

helm create hello-world

Changed image name and deployment name in deployment.yaml

kind: Deployment
metadata:
  name: mytomcat
spec:
      containers:
        - name: {{ .Chart.Name }}
          image: tomcat

Install

helm install hello-world

NAME:   whopping-dolphin
LAST DEPLOYED: Wed Aug 30 21:38:42 2017
NAMESPACE: default
STATUS: DEPLOYED

RESOURCES:
==> v1/Service
NAME                          CLUSTER-IP  EXTERNAL-IP  PORT(S)  AGE
whopping-dolphin-hello-world  10.0.0.178  <none>       80/TCP   0s

==> v1beta1/Deployment
NAME      DESIRED  CURRENT  UP-TO-DATE  AVAILABLE  AGE
mytomcat  1        1        1           0          0s


NOTES:
1. Get the application URL by running these commands:
  export POD_NAME=$(kubectl get pods --namespace default -l "app=hello-world,release=whopping-dolphin" -o jsonpath="{.items[0].metadata.name}")
  echo "Visit http://127.0.0.1:8080 to use your application"
  kubectl port-forward $POD_NAME 8080:80

I see mytomcat deployment and pod mytomcat-2768693561-hd2hd in dashboard.

Now I would like to give command which will delete my current deployment & pod in k8s and it should create new deployment and pod.

It will be helpful if I get sample commands and yaml.