Hello and thank you for checking this out. 
I have finished building a small IOS game and want to upload it with Game Center leader boards/achievements and i-ads (but I just want to talk about GC) 
I have downloaded a plug in called IOS SDK plug in LITE. It's free and I like the buttons. 
 https://www.assetstore.unity3d.com/#/content/12508I have set everything up as far as itunes connect and I have managed to use this plug in and get everything to work in the sense that: 
1.) I have a button at the start of the scene and when you press it signs you in to Game Center (and I am in sandbox) 
2.) When you press start it takes you to another scene and the game starts - when you die - that camera shuts off and another one turns on showing you the SCORE which is a Var Int (global) lets call it NinjaScore 
 And Two new buttons: One to send the score and the other to show the leader boards. 
My question is, am I suppose to put my Var NinjaScore somewhere ? How does it know what the score is ? And When I look at the leader-boards it just shows 1 
If there is any info I am forgetting to post please let me know... And any help would be appreciated.