how to add the AdSense code in googlepages

hello, everybody!

i created a personal website at googlepages. but i dont know how to add the code about AdSense in my homepage at googlepages.

this is my personal website: http://drivehq.jay.googlepages.com/

you can see the homepage, i have no idea add the code about AdSense in it,
but i add the code at the sub-pages, cause i created them with HTML and then i upload at the space.

so i wanna ask you how to add the AdSense code in homepage at googlepages.

thanx a lot