Chart overlays where both X and Y are very different

I know this can be done - I have spent far too long trying to duplicate the sample graph noted in the attachment. Can someone please take a look? I have been working at this and watching you tube videos... I figure it has to do with the X axis since one data series has many points compared to the other series with only a few ... I want the two series to overlay over each other ..... so it looks like the picture graph at the top, which I need to update. Your help would be appreciated.