ArcGIS Pro 2.5 - How to create a style

[KeithAddison2]

I'm trying to set up a style in ArcGIS Pro and I've gotten as far as creating the style file in the catalog window and adding some items to it.  I can't seem to figure out how to actually edit the symbology though, as in change the red circled default black line to anything else.  Right click and double click anywhere on the lines symbol entry row doesn't get me there, there doesn't appear to be anything like that in the panes.  What am I missing?  Is this done from somewhere else?