Easiest way is to create a quest and attach a script to it. Make sure the quest it set to start game enabled the use a script like this...
scn MyQuestScriptshort onceBegin GameModeif once == 0 player.additem MyItem 1 player.addspell MySpell set once to 1 stopquest MyQuestendifEnd
Create the quest first then close the quest window. Then make the script and save it as a quest script. After that you can open the quest back up and select the script. Substitute your item/spell/quest names where I put myitem etc...