How to play Ruy lopez

Learn theory

Dont play ruy lopez as a beginner, go for simple openings that does not require learning a lot of theory. You can try scotch, london scotch gambit or kings indian

Just don't, learn an easier opening, ig london, italian, scotch/4n scotch, vienna etc

queen's gambit a very good one though

This is the main line but there are other lines. You don't need to learn loads of theory, you just need to understand the ideas. White applies pressure to e5 by threatening to take the c6 knight in some lines. When white defends e4, they are threatening to take on c6 and then e5.

Even though it seems that white gives black the moves a6-b5, these moves can often prove to be a weakness as it leaves the c6 knight undefended and the pawns can later be targeted with a4.

Then white wants to play c3-d4. This is much riskier in the Italian as black has d5 with tempo on the bishop which isn't possible in the Ruy Lopez.

Against the Berlin Defence, I would simply recommend the move 4. d3. This avoids the Berlin Endgame and makes it a lot simpler.

There are a lot of variations but that's what can make it a fun opening and you can find a comfortable setup against each one.

Against the Steinitz, the typical plan is d4-Nc3. White is doing well here as black is very passive.

Against the Schliemann this line is good as it prevents black from castling which slows down a lot of black's attacking ideas.

As Black in the Lopez, don't get carried away snatching Pawns.

First of all, the notion that you should not play the Ruy Lopez as a beginner is asinine.  It is one of the most straightforward and classical openings for White.  The irony being that recommending the Italian while discouraging the Ruy makes no sense as they are effectively siblings.

The first several moves of the Ruy Lopez revolve around attacking and defending the e5 pawn.  If both players continue down that path, they eventually reach a point where there is no longer a way to attack nor defend e5 any more, and then play shifts.  White can play on the queenside, center, or kingside, depending on tastes as well as depending on what Black does.  Black's main ideas involve challenging the center and/or attacking the kingside.

THANKS EVERYONE

That's understandable, but if I ever play d3 in a Ruy Lopez, I always switch tactics and play a d3 Ruy Lopez instead of a c3 d4 Ruy Lopez, so c3 is an odd move to me, can you explain it?

c2-c3 covers a vitally important square, whether or not you follow it up with d3-d4.

Also, it allows the White Bishop more latitude... eg: Bc2 and then d3-d4.

Ohhh, blocking the knight from going to b4 or d4? That makes sense, although wouldn't the knight be going to a5 anyways?
As for the second reason, I'd argue that it's a bit slow, as d2-d3 c2-c3 d3-d4 gives Black an extra tempo compared to c2-c3 d2-d4, so I'd play much more passively with h3 Bb3 0-0 Re1 Nbd2 Nf1 Ng3 a4, with ideas of attacking on the queenside or forcing Black to play more aggressive.

Well, yes... but if you are playing for c2-c3 and then d2-d4 (in one step) then you have to do it (and risk an open center) while half of your army is still on their starting squares... yes? NONE of your QR, QN or QB gets to move while you have Pawns sitting on d2 and c3.

While the alternative I suggest is to play d2-d3, c2-c3 (now the center is kept under control), then get castled, develop your WHOLE army, or at least as much of it as you like (eg: Nb1-d2-f1-g3)... and only when you feel completely ready do you play d3-d4.

A lost tempo on move 12 or move 15, when you are completely developed anyway, is NOT the same thing as a lost tempo on move 5.

Additionally, it opens up the c2 square for the bishop to retreat to should Black play the Na5/c5 plan.

all of these worthless names for openings are old arcane and useless 

don't fool yourselves none of it will help you.  

read a book instead and do something productive.

Why do cities have names? Why aren't they just called "City A1", "City X11", etc.?

Surely these worthless names don't help us.

Probably our own names are worthless and we should just be called by our citizen identification codes, "Citizen G56JX99". Names are unimportant after all.

Why do football teams have colours when they could have 2 outfits for every game, white and black? Wastes less dye. They should also just be called Team 1 and Team 2 as names serve no purpose in the new world.

Why do words such as "brilliant" and "magnificent" exist when they could be replaced with "+ good"? To express even more emotion one could say "double + good"!

double plus ungood suggestion.

Perhaps even... "triple - good"