error-add to cart

Hi,
when I click "add to cart". I meet some errors as follows.
http://www.martdo.com/index.php?route=p ... oduct_id=9

Notice: Undefined index: option in /home/content/c/h/a/chatpie/html/web/martdo/catalog/controller/product/product.php on line 5

Warning: Cannot modify header information - headers already sent by (output started at /home/content/c/h/a/chatpie/html/web/martdo/catalog/controller/product/product.php:5) in /home/content/c/h/a/chatpie/html/web/martdo/library/system/controller.php on line 89

my opencart version is 1.0

please give me a hand, thanks.

First step. Delete 1.0. It is not meant for store use, more as a  "developer preview"
Second step. Get the latest 0.7.x release. That is the stable code

Thanks. when will the 1.0 version be stable?

Well only Daniel can say when the next version will be ready. But it is a completely new framework from 0.x so all the same bugs plus new bugs can exist in 1.x.

0.7.9 is the most stable version in existence, and its been 2-3 years since 0.x was started...
so... 2-3 years sounds like a good timeline for 1.x stability