The parts of inner game are simple. Confidence,beliefs,character, and your overall attitude of life. Let me give you examples of how just having confidence wont work.
EX1; Lets say your talking to a woman are very confident and dont have your beliefs in control. Out of nowhere she decides to test you and says wow your a douchebag. If you believe that you are a douche bag your confidence with women will go down. On the other hand lets say if somebody says your an old man you will laugh at them because you know your not an old man and wont give a shit. This a huge factor of somebodies inner game.
EX2; Lets say again, you are very confident but your view on rejections and life isnt the best. You view rejections as failures rather as learning experiences. Well a person with strong inner game would view those rejections as learning experiences and not failures. He wouldnt make the same mistake again and would analyze the situation and what went wrong so it doesnt happen again.
You can have instant confidence just read the book unstoppable confidence by kent sayre. This will give you confidence but the results arent permanent and youd have to keep doing the exercises over and over again. Which isnt fun and after a period of time youll quit. But... If you arent congruent with your confidence then people will pick on that and say something really cruel or rude that will hurt you if you dont have strong inner game. Lol, learned from my experiences

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An example of how I did some confidence techniques and exercises which lead to hurt,shame, and shitty feelings. I was at school looking for self help and confidence building tools and techniques. Found some techniques and exercises and applied them. After that I went out and noticed a change in my walk prior to doing them. I didnt like this walk. I didnt feel that im congruent with this walk. So im going to my locker take my stuff and head home. on my way to heading home some kid says "He walk like he the shit". This hit me really hard and for about 2 days after that I wasnt at all confident in my walk and felt as if I walked like a stuck up or arrogant douchebag. This happened because I had big holes in my personal boundary and little shit got under my skin. Today that is not the case
Hope this helped out