If I taught you to setup Wi-Fi hotspots manually than it will be a long tutorial with lots of messed up steps which you might not welcome to. Moreover you may get stuck on the way.
I found a called Connectify which can easily turn your Windows 7 Desktop into wireless router just by a single click without the need of any wireless router.
To obtain a to fill up this form in their . Thedownload link will be sent to your email address. for Connectify, you’ll have
Or, you can download it Download.com . Download and install Connectify. from
Select the Internet connection you wish to share.
Choose a name for your new wireless network name it to anything you want. Choose a password to authorize access after inputting password from other computer.
Press the Hotspot On button to turn on your wireless network.
Now, from your other Wi-Fi enabled devices, you can see your wireless network. Choose to join it, and enter the wireless password to connect.
Please note that this beta program only runs in Windows 7 and it doesn’t run in lower version of windows, not even Windows Vista.
Hope this tutorial was useful