yeah main one I use is via add-ons on PC. I use combat metrics: https://www.esoui.com/downloads/info1360-CombatMetrics.html It is pretty great, tells you your DPS, DPS % when in a group and lots more detailed stats. So in battle yesterday could see group DPS and my % of that and get an idea of everyone else's.
Without that, only way is to check by doing target practice on dummies. You need to craft them though and usually need to be higher level / a lot of material / gold, so usually most people will join a bigger guild and visit the "guild hall" I have a few in my home which I mentioned above and happy for people to visit and use. Though with that said, even then, its more of a method to refine your rotation and make sure you can sustain damage over a longer term then anything else, but it does provide dps report.
I think there is something called minion tool which makes working with add-on's easier, not used it myself, used to the manual route, but @dan958 has mentioned it a few times so may be able to advise.
I use minion. You tick want you want and it auto installs. It wasn't working until Nutty pointed out that in the details section each add-on requires some basic add-ons for them to function. I downloaded them last night (just ticked a few boxes). Will test today.
I will prob get the one you're recommending. I'd be curious to see how much damage I'm doing and try different builds on your dummies!