Share internet through Dell laptop Windows 7

If you have a wired connection to your laptop, you can use it to share your internet wirelessly, by creating a wireless hotspot...

VirtualRouter or Connectify will do this.

Virtual Router is a free, open source software based router for PCs running Windows 7 or Windows Server 2008 R2. Using Virtual Router, users can wirelessly share any internet connection (Wifi, LAN, Cable Modem, Dial-up, Cellular, etc.) with any Wifi device (Laptop, Smart Phone, iPod Touch, iPhone, Android Phone, Zune, Netbook, wireless printer, etc.) These devices connect to Virtual Router just like any other access point, and the connection is completely secured using WPA2 (the most secure wireless encryption.)

Another option is an ad-hoc network. Step-by-step tutorial from Microsoft:

Set up a computer-to-computer (ad hoc) network

I've used ad-hoc networks successfully to share Internet wirelessly.