How do i put a humanoid in a player? [closed]

Humanoids are put in players' characters when the players' character is made. You don't need to do that unless of course you're creating an NPC in which case you need to create a new Humanoid instance using:

Instance.new("Humanoid",game.Workspace.NPC)

If you want to adjust the jump power of all players the easiest way to do this is using a Server Script you will need to functions one to run when a player is added and another for when the players' character is added. Here's the script:

game.Players.PlayerAdded:connect(function(plr) -- When a new player joins
    plr.CharacterAdded:connect(function(char) -- When the players character is created (on death and on join)
        local hum = char:WaitForChild("Humanoid") -- Find the humanoid
        hum.JumpPower = 150 -- Change the Jump Power
    end) -- End the character added function
end) -- End the player joined function

Hope this helps, if this works for you please vote up and accept as answer. If this doesn't work or isn't what you expected, please comment and I will edit this answer.