How to show Average by week or month with week/month on the X axis?


Am running Prometheus v2.2 back-end and using Grafana v5.2.3 to graph metrics.
I would like to average some metrics and display them on a bar-graph as weekly or monthly averages where the week/month is on the X-axis.

I tried doing this with the Grafana “Graph” panel using the Query "Min-step and Options “Min time interval” but am not getting it right.

Is there a way to do this and if so how ?

Thanks in Advance