Adding New server to monitor on grafana dashboard

I am new to Grafana and I gave a system that is already setup with Grafana and Graphite both installed on docker containers and collectd and rrd installed on the machines.

Dashboards are up and running on all these systems and I would like to add a new system to monitor.
I’ve already installed the collectd packages and edited the collectd.conf file to point to the grafana server and everything.

I am not able to add this server to the list of servers in the drop down menu in the existing dashboard and I am not able to add a new variable for this server from grafana dashboard.