what was a better second step than nc6 ?

 For black ?

d6 or Bd6

Almost any move that saves the e5 Pawn would be better.

2. ... d6 is the most common move. Even 2. ... Bd6 (intending ... c6 followed by Bc7 and d5) might be better.

One humorous line:

I don't like bishopd6 it blocks your light square bishop developement

The intended sequence would be Bd6, then c6, then Bc7, then d5. How does that block the LSB?

But whatever...

nice 

but the opponent should play f4 for this to work

Bd6 is not the best, not just because it temporarily blocks the d pawn, but because it plays for a trap.  BXB4 looks fine instead of trap chess.

can you say the say name of the trap please ?

Mappy56, not everything in chess has a name, nor is it important to know a name, should it exist.  What is important is seeing the open e1-h4 diagonal.  This idea is used in many openings.  That is why it is important to understand the idea of an open diagonal for checkmate. By the way, the idea comes from the fool's mate pattern.  Hope that helps.

fool mate only works when your opponent is foolish enough to play f4  or f5 .Bd6 doesn't invite fool's mate yeah it does block d pawn i can agree on  that  .https://www.chess.com/article/view/the-fastest-possible-checkmate-in-chess

F4 and f5 are playable moves.  They  are not foolish moves.  But they are risky, even when played as a system.  

with all do respect ,what does it have to do with playing Bd6 ?

It isn't playing for a trap... it's playing for a center duo (e5+d5) after Bd6 followed by c6, bc7, d5, etc.

i think d6 is better it does blocks your light square bishop 

If you wish to play for a center duo, you may . But consider that you spend 3 tempi to get your center duo.  What do you think your opponent will be doing for three moves?

gosh, can you even read more than two sentences.

blueemu said explicitly "it's playing for a center duo (e5+d5) after Bd6 followed by c6, bc7, d5, etc." doesn't that addresses the problem of the light squared bishop?

to Nwap11: while Bd6 does contain a trap, its a good move. trap chess is bad if you are plating inaccuracies just for the sake of setting up a trap. in fact, most good moves contain a trap because you can never refute a good move. 

But yes. Bxb4 is much better. another easy way to play against b4 is to play 1...c6 followed by 2...a5, attempting to damage white's queenside pawn structure. But against b3, there are a few key lines where bad6 is the best. and it's important to know that?

EDIT: replying to #16, white cannot do anything to stop the plan of c6, bc7, and d5. Nf3 is met by Qe7, while f4 leads to the line in #3.

Count the tempi you are using to set up the duo. Three tempi, which theory equals a pawn.

"three tempi equals a pawn" is a well known phrase, but its never a theory or a rule. 

if your opponent can't do anything with three tempi, are they up a pawn?

Very few positions can you waste 3 tempi in.  If the game is locked up or the center is closed, then you are right.  But think what you would do in this position if your opponent handed you three tempi.