You may follow Using Helm with Amazon EKS from the Amazon EKS official document or just follow the steps below:
# install helm cli
$ curl -L https://git.io/get_helm.sh | bash
# create 'tiller' namespace
$ kubectl create namespace tiller
# open a new terminal and run tiller client mode
$ export TILLER_NAMESPACE=tiller
$ tiller -listen=localhost:44134 -storage=secret -logtostderr
# open a new terminal
$ export HELM_HOST=:44134
$ helm init --client-only
$ helm repo update
That's all!