Can I use my PC as a WiFi router?
Solution 1:
You might want to try Connectify.me.
Meet the app that lets you transform your laptop into a Wi-Fi hotspot at the click of a button.
Solution 2:
In short... No. Here's why: 99% of consumer-grade wifi adapters and their drivers do not have any capabilities to perform the necessary "Access Point" bits. Manufacturers deliberately remove that functionality. That remaining 1% of devices out there that do offer AP functionality are either poorly-designed hardware and software, or are insanely expensive and require a server-OS of some flavor.
That being said... more-often, you can find support in Linux for a much larger selection of hardware to implement the AP bits... or you can simply buy a cheap $15 access point and save yourself $1000 worth of headaches.
Solution 3:
One way is to create an adhoc wireless network.
See article: Share an Internet Connection Between Wireless Machines with an Ad Hoc Network in Windows 7 at How-To Geek.