I've been playing Chess for over 40 years. In my first 5 years, I went from beginner to OTB Master by tutelage, constant study, review, pickup games & extensive tournament play (with a couple of years with more than 200 USCF games per year). Over the past 12 years or so I have played hundreds of correspondence games (not on this site) with a very good record (On one site, My stats: + 541 = 133 - 127). Many openings require a great deal of knowledge and experience. The Ruy Lopez Marshall variation is heavily analyzed. The Marshall variation starts at move 8. An excellent book, Bologon's Ruy Lopez (for Black) 2015, by Victor Bologan (part III, p 247) explains the Marshall with its many variations as well as alternative variations that avoid it. So, as Black, not only do you need to know the Marshall well, where some variations are 30 or more moves - you also need to know another 17 variations of the Ruy Lopez that go 20 or more moves. Sure, you can wing it for many sub-variations, but only if you already understand the opening's basic principals. (Note, of the hundreds of books I own, BRLfB, is probably the best. If you're a beginner then I recommend Leonard Barden's The Ruy Lopez, Winning Chess 1P-K4, mine is the 1971 reprint.) However, if you don't have an extensive library of games or opening books you are at a distinct disadvantage. This would be akin to someone building a Web server from scratch, where they would need to develop the programming libraries for the OS... not impossible (improbable) but why ignore all that pre-built knowledge... I can go online download a LAMP server, configure it and have it ready to go within a couple of hours (give or take some time based on its purpose). Of course, this is a simplistic view as there are many types of applications and integrating them can exponentially increase the complexity (think cloud applications). Similarly, Chess is not always so easy and it requires a great deal of hard work. Get the books (if no money then search Google or other archives), download pgn games, review and study alternative variations, get familiar with the positions you like to play; figure that out and you will get better. By developing a plan regarding what you play will help your play here or at home or at the club or at an OTB tourney. Hopefully, the time spend is rewarded.