I can't create any commands.

[xoft]

Your callback is wrong. The first parameter the command callback receives is the Split - the text that the player entered, split at each space. The second parameter is the cPlayer object.

-- PluginInfo
function PluginInfo(a_Split, a_Player)
        a_Player:SendMessage("§eSTONED v1.0.0.3")
        return true
end
 
-- RollJoint:
function RollJoint(a_Split, a_Player)
        if (a_Split[2] ~= nil) then
                -- The player gave us a parameter for the command:
                cRoot:Get():BroadcastChat("§b" .. a_Player:GetName() .. " is rolling a joint with an extra " .. a_Split[2] .. " inside.")
        else
                -- There was no parameter, so it's a simple joint:
                cRoot:Get():BroadcastChat("§b" .. a_Player:GetName() .. " is rolling a joint.")
        end
        return true
end
 
-- SmokeJoint:
function SmokeJoint(a_Split, a_Player)
        cRoot:Get():BroadcastChat("§b" .. a_Player:GetName() .. " is smoking a joint.")
        return true
end