How to use a simple .chatted script?

This should all be in a regular script in ServerScript service

Now there are a few problems with your script. First of all, this would instantly error if the player "Abysswalk" wasn't in the game when the script loaded. So in order to get this to never error I would suggest the PlayerAdded event. Like so,

game.Players.PlayerAdded:connect(function(plr)
    plr.Chatted:connect(function(msg)
         if msg == "Spread" then
                 -- right here I tried to make my humanoid jump but it wont work
        end
    end)
end)

Okay, now when any player joins the game and chats the Message "Spread" the commented area will activate. Now, if you're trying to make the character Jump when this is Chatted then you would get the character from the player using plr.Character.After that, you would find the Humanoid of the character and activate the Jump property. Like so,

game.Players.PlayerAdded:connect(function(plr)
    plr.Chatted:connect(function(msg)
         if msg == "Spread" then
                plr.Character:FindFirstChild("Humanoid").Jump = true -- makes Player's character jump.
        end
    end)
end)

That should work BUT, if you want it to only work for you, you would have to check to see if the player's name was the same as yours. And because when testing on Roblox Studioyour characters name is always just "Player" you should also add that for the check as well. Like so,

game.Players.PlayerAdded:connect(function(plr)
    plr.Chatted:connect(function(msg)
         if msg == "Spread" then
            if plr.Name == "Abysswalk" or plr.Name == "Player"  then -- also checks name
                plr.Character:FindFirstChild("Humanoid").Jump = true 
            end
        end
    end)
end)

Hope that helped! Good Luck!

The wiki is an amazing place

.chatted with examples

chat commands

local char = game.Players:FindFirstChild("Abysswalk").Character
game.Players.Abysswalk.Chatted:connect(function(msg)
    if msg == "Spread" then
        char.Humanoid.Jump = true
end
end)

try that it might just work

also make sure if your testing it online if it doesn't work it might need to be a local script