Cert-manager and Rancher 2.0?

I setup Ingress shim with cert manager and it works.
When deploying a new workload, cert manager added one service discovery and one Ingress Load Balancer, both called cm-acme-http-solver-xxyy.
Now I have no idea howto use it with the domain and get the letsencrypt cert. Please visit this post and see if you can help.
TY