My opponent had superior endgame... what could I have done differently?
Oh, it didn't post the whole game, sorry, I'll get that up here. Just a sec.
Edit: After trying a few times, it will not work. I'll try one more time.
Alright, just forget this exists. It isn't working right.

You actually had the superior endgame after 24 ... Kf7. 25 RxR QxR 26 Qb7+ gives you the active Queen. It is still probably drawn, but the big pieces need to be active, not passive.
In your opening, Qxd4 was bad. Developed queens in the openings tend to become targets. Yours got kicked all over the place.
IMO the best endings book for new students is "How to Win in the Chess Endings" by I.A. Horowitz. It's not a reference book, it's a book for learning the basics. It teaches them very well.