How Do you become confident?

So i went out to the bar the last couple of nights.. I love going out cause i really dont care. I go out and just let Go and be and dance and laugh.
But i have to say that was sorta surprised when a guy came up to me and told me he could tell i wasnt confident with myself. Me being me laughed and said YOU DONT KNOW ME and took a hug drink of my beer.
Im not. I suck at believing in my self. This has been something i struggle with Massively ever seen high school..cause thats where it started. In middle school i didnt care. I was funny and loud and cool cause i could draw.. then i went to high school and it changed. suddenly i realized the kid next to me could draw better or make some one else laugh more. I became REALLY insecure.or at least thats what i would like to think happened! I then went to work the next day and asked my best friend.. How do you become confident? " I dunno you just do" Really? is it that easy? I just wake up one day and all my insecurities are gone? I can not care about my weight or that im cross eyed? The things i massively worry about i can just be done with it? HA there is no way that something like that can happen over night. I get very frustrated with myself. Why cant i stay on the diet? why am i so shy to try new hair things? Why cant a wear something That isnt nasty tight but tighter then a baggy t-shirt? Maybe if i start slow?
So i tryed it. I was invited to go out once again with my cousins. This time they started at the Ale house. which i sorta know is where all the pretty people go. I got ready took my time to curl my hair and to do my make up. I put on my favorite high heels, and jeans and wore a tight shirt that showed me off. ( again not in a nasty way)
As i drove down there i was TOTALLY scared. I sat in my car for an hour trying to gt the nerve to walk in to that building. My cousin had to come out and get me tell me how nice i looked and tell me that i didnt need to go home and change. i then became SO mad at myself. If i a weird guy could see thru me how is a tighter shirt going to change how i feel? Did i get hit on? No did i get a number or a drink? No. it was the same as it always is when i go out. Im invisible. How do i find the happy medium of being confident? How do you even start with something like that? If i really lose weight will i be happy? Or will i find more things about myself that I TRULY cant stand? Im not saying i want to become a hooker and have boys drooling all over me. I simply want to walk in to a room where i feel confident and to have some one in return notice me. Im very mad at myself. Im frustrated. I want to move on with my life. It seems like so much holds me back. What do i have to do to break free what the chains of the this world holding me down? I guess im going to have to find the "how to become confident for dummies" book... eh.