Good grief! Nobody here is helping this poor chap! I dont know much about the item id stuff, but maybe you can make scene of it. Anyways heres the link for potion id's. http://www.minecraft...Item_id#Potions
Umm, how about the ID for trying to give it to yourself, not via command block?
Wait a minute, sorry! How you obtain the night-vision potion is /give "Player_name" 373 "Quantity" 16390
/give Xenon_Fesk 373 64 16390
You can use this with other potions too, heres a site or all item IDs: http://www.minecraftinfo.com/IDList.htm
Good luck, minecrafters!!!