This will give you the easy installation of the Prometheus and Alertmanager deployment
To add this repo in your local helm repo
helm repo add prom https://mohanagandlla.github.io/prometheus/
helm repo update
Prometheus operator > 0.44.0 deployed in your cluster along with CRDS if no operator deployed then folllow the link https://github.com/prometheus-community/helm-charts/tree/main/charts/kube-prometheus-stack
helm install [release name] mohan/prometheus -n [namespace name]