Best way to study a repertoire?

IMBacon is generally right when he said that you shouldn't be learning openings at that level based on your displayed level. Now we don't know what is your level on li... competitor's site, but bear in mind that their ratings are roughly 200 - 300 points higher than chess.com ratings. If you are not around at least 1 200 here or at least 1 500 there, you shouldn't think about concrete openings at all. You should know 3-5 moves to get the variation you wish to play, and just play on from there. Even 1 200 here should only mildly look at opening explorer after they finish their games (I said mildly, so you shouldn't memorize lines then, but to just take a peek at the explorer).

At my level, which is around 1 550 - 1 600, I still don't need to memorize things. I did memorize some moves just by looking opening explorer and playing games, but that is mainly because I've played games and naturally accumulated some small knowledge. 

Actively memorizing lines is mainly for advanced players (those over 1 800 chess.com ratings or over 2 000 ratings at that other place). These players know why are they playing certain moves and memorization comes a bit easier then.

Players below this have a lot of work to do before learning concrete opening lines. 

First -  general opening principles and avoiding blunders in equal or better positions
After that - all the rest, but there are many things before memorizing long lines. Things like tactics, basic endgames, then more difficult ones, positional stuff like which trades are good, pawn play and how to exploit weak squares and so on. Along with that, when you feel you know something beyond the mere basics, when you play a longer time control game, you should analyze it - at first it will be a simple blunder check and afterwards it would be a more refined analysis.

At this point, you can look at the opening explorer as well after each game in order to see if you've made some mistake in the opening which gave the opponent much better game  (only when you really understand opening principles and follow them, and when you don't just make big mistakes in every game).

By the time you get better at things I've mentioned, you will be better at opening play naturally, and you will know some moves in the openings you are playing. After some of the things I've mentioned, you can look up some master games in the openings you are playing, and still not learn 15 + lines but look at those games in order to find strategy plans, which pawn pushes are thematic, which common tactics occur in those games and so on. 

If you are able to do all of that, you will surely be pretty good and you might even want to learn some concrete lines by heart to give you the edge.

What I've said is not written in stone, but in any case you need to learn how to walk before you start running. So you can change up the order of studying to your satisfaction, but you have to get the hang of mere basics before anything else, and you should leave memorization for the time you are already at least intermediate to advanced player.

I will the story i post here repeatedly.  There was this young man that all the local masters said would be a Master by the time he turns 13.  He was 10 at the time.  So what happened?  He fell in love with openings.  He suddenly became "aggressive" and "tactical".  And when he lost it was the same excuse: "I forgot my theory" "I mixed up my opening theory"  When what happened was that he dropped a piece.  He finally quit playing as an 1800 player.  A lot of potential down the drain.

Now this is a helpful perspective. Thank you .

Thank you to those who were constructive and helpful. Special thanks to those who pointed out, constructively, that it might be too soon to worry about such things, and presumably care about a beginner's overall path. As for those who were less constructive, after researching several posts by others, that seems to happen a lot on here. Seems sad to me. I have many thoughts and feelings, most of them equally unproductive, so I'll toss them in the toilet where they belong.

By the way, you have diamond membership. Make sure to take advantage of the video library, because that is the main advantage of diamond membership over other membership types. 

Forget what anyone says. It's important to have at least a basic understanding of openings, not in terms of memorizing moves, but knowing what the general ideas are in a variation, what are some ways to get an advantage in the midgame and avoid your opponent's threats, or launch a counterattack, or get a sense for piece play dynamics (e.g. trading off your "bad bishop" for his "good knight"), or aim for a specific pawn structure that might be beneficial for you in the endgame. Think of it this way - if you and an opponent have a similar rating, but one of you has a better idea of how to play the opening that's on the board, chances are he or she will get a better game. And against stronger players having the confidence that you are sort of familiar with some openings will give you somewhat of an even playing field. Far too many players walk into opening traps or just get a permanent weakness after the first few moves (and then suffer against most good players who will make you fight to just get a draw!).

Openings aren't the silver bullet to improving your overall chess skills, but they can definitely help guide your progress.

He will do that by studying games in the openings he chooses (after getting the hang of basic stuff), as I've mentioned in my post.

IMO that comes later, after you have some experience and have studied strategy. A new player can't make use of these things yet.