I can’t able to use my iPhone as a Wireless Laptop Modem.

Dear All,
I'm using iPhone 4G and Apple Macbook pro. I travel lot and always need to be in online. iPhone has a very good screen with a very good resolution but the thing is, you know sometimes I need to view my mail and attachment which is not sufficient in iPhone screen. So, I need to view it in my laptop screen but I can't able to connect my iPhone with my Laptop as a modem. Is there anyone who can help me to give me instruction how can I able to use my iPhone as a modem.
Regards,
Akash
