The Way You Cum

So all my life I have only ever came Vaginally once! Once! And I never knew how I did it. I can only cum by rubbing my clit the whole time and sometimes it's just a hassle because some positions make it harder for me to reach it or it won't work because it's overstimulated. How can I go about practicing or teaching myself how to cum Vaginally? It would make my sex life a whole lot easier and more fun! I'd highly appreciate advice/tips on this!