How to graph two two data points on a single graph

Hello,

We're trying to represent the number of Zoho desk tickets opened and the number of desk tickets closed each month on the same graph.

We're looking to create something like this:

With perhaps the blue area being the number of tickets opened, and the grey being the number of tickets closed.

I'm not sure what to make the X axis, as I'm looking at both ticket create date, and ticket closed date.

Do we need to create another table that somehow counts each of these values in a row dedicated to a date, then graph that new table?

Thanks in advance for any ideas!