And for your script: 
  
function teleportarPlayer ( source, posX, posY, posZ ) 
        getPlayerFromName ( source ) 
        getElementPosition ( source ) 
        setElementPosition ( source, posX, posY, posZ ) 
    end 
    addCommandHandler ( "goto", teleportarPlayer  ) 
  
 
source is not able to use it as paramater. change source -> theplayer or else. 
player (element) = getPlayerFromName(thePlayer or else) you get a player you can use but thePlayer or else is already a player which use the command. 
x,y,z = getElementPosition(thePlayer or else) you`ll get the position of the player but not needed here. 
setElementPosition(thePlayer or else, tonumber(posX), tonumber(posY), tonumber(posZ)) tonumber() becouse you give a string ( a text ) and text is not a Integer