This is my first tutorial and I am gonna teach you how to make your own kits or classes in minecraft without any mods, texture packs, or external editing clients. Just look above in the pictures to learn!
Hope it helped!

To Get A Command Block, Enter A Single Player World And Type /give @p 137 (or type this) /give (player name) 137

When I Say The Picture Above, I Mean The Picture To The Left

CONTINUED FROM THE LAST PICTURE: Now Drink A Potion of Strength And Hopefully You Should Get A New Inventory. Add Another Chain of Command Blocks To Create Another Inventory But With A DIFFERENT NUMBER In /effect @p 5 0 CHANGE THE 5!!! You Need To Experiment With The Numbers So You Know What Potion Is What /effect. If You Are Confused, Please Comment Saying I AM CONFUSED

-Themonkeystaff

Also, check out this link http://www.planetminecraft.com/blog/scoreboard-tut/ on a really useful tutorial to make scoreboards! (Not Mine)