Ok soo this explanation sucks due to many ways. Bassicaly, just keep in mind to NEVER EVER ABSOLUTELY NEVER UNDER ANY CIRCUMSTANCES DO YOU ALLOW Nb4. That is it! have fun.
General ideas:
d3 to disallow e4 push and make room for the b1 knight.
Qc2 to unallow e4 push.
e3 allows you to develop your bishop (And also prevent Nd4 NEVER ALLOW THESE 2 MOVES OKAY? this is a very common mistake.)
Nimzo larsen.

Nimzo larsen opening is a opening that has a good fundamental base and does not require alot of practice.
In this position, Stockfish gives us an advantage. Why? Find out!
Next lets look at the E5 variations. The modern variation and probably the best handle of the nimzo larsen.
A3 was to prevent ideas of Nb4 as it is actually a really big threat you should be on look out. Be6 black is trying to go for a english attack. Stop it with Qc2.
This is getting way too complicated isnt it?
Anyway soo ask your questions about specific replies that the enemies may or may not do, And ill try my best to answer them!