Lua Im learning and i need some help with functin onadditem

[megachock]

Hey guys, im learning how to make scripts, i have some doubs
Explained.
I want if some items are in a correct position and you use the lever it will teleport you to a position.
I want to learn if you post the script please teach me how u made it =) i have seen many guides but they dont explain all functions

function onUse(cid, item, frompos, item2, topos)
position={x=200, y=200, z=7, stackpos=0}
position2={x=250 y=250 z=7}
if getThingFromPos(position) and item.itemid == 2828 then
doTeleportThing(cid,position2)

For example if in map is the item 2828 in the pos x=200 y=200 z=7 and 2929 in the pos x=201 y=200 z=7 then
doTeleportThing
for teleporting the player to a position
How i do it? i mean i put the action id in the map tiles right?..

 

[Summ]

function onUse(cid, item, fromPosition, itemEx, toPosition)
  local thing1 = getThingFromPos({x = 200, y = 200, z = 7, stackpos = STACKPOS_TOP_MOVEABLE_ITEM_OR_CREATURE})
  local thing2 = getThingFromPos({x = 201, y = 200, z = 7, stackpos = STACKPOS_TOP_MOVEABLE_ITEM_OR_CREATURE})
  if thing1.uid > 0 and thing2.uid > 0 and thing1.itemid == 2828 and thing1.itemid == 2929 then
    doTeleportThing(cid, {x = 250, y = 250, z = 7})
  end
  return true
end

You set the 2 positions where the item has to be, stackpos is important here. STACKPOS_TOP_MOVEABLE_ITEM_OR_CREATURE equals 255.
Then you check if there are items on the tiles you set and finally check if the itemids are correct.
Script is not tested

 

[megachock]

function onUse(cid, item, fromPosition, itemEx, toPosition)
  local thing1 = getThingFromPos({x = 200, y = 200, z = 7, stackpos = STACKPOS_TOP_MOVEABLE_ITEM_OR_CREATURE})
  local thing2 = getThingFromPos({x = 201, y = 200, z = 7, stackpos = STACKPOS_TOP_MOVEABLE_ITEM_OR_CREATURE})
  if thing1.uid > 0 and thing2.uid > 0 and thing1.itemid == 2828 and thing1.itemid == 2929 then
    doTeleportThing(cid, {x = 250, y = 250, z = 7})
  end
  return true
end

Nice really thanks i think now i understand a bit the scrpt jjeje, what do that stackpos?
and if im not bad this " if thing1.uid > 0" means if the item1 unique id is high to 0
for what is that? and if i put if thing1.uid == 5002 and... this is if thing 1 have the uid 5002 right?

also i made this one: when u pull a lever remove item from a position is it correct?
Thanks a lot for your help

function onUse(cid, item, fromPosition, itemEx, toPosition)
pos={x = 201, y = 200, z = 7}
wall=2000
         if item.itemid == 1945 and getPlayerLevel(cid) >= 50 then
                doRemoveItem(getTileThingByPos(pos,wall)
                doPlayerSendTextMessage(cid,21,"You removed the tile !")
		doTransformItem(item.uid, item.itemid + 1)
	elseif item.itemid == 1946 and getPlayerLevel(cid) >= 50 then
		doPlayerSendTextMessage(cid,21,"You have closed the pass!")
		doTransformItem(item.uid, item.itemid - 1)
                doCreateItem(wall, 1, pos)
return true
end

- - - Updated - - -

Check please :/