Follow these steps to create wifi hotspot in windows 7 laptop without any 3rd party software:
1.) Click on the right side on wifi icon of the windows task bar and then click on open network and sharing center.
2.) Then after the first step under the option change your network setting select set up a new connection or network..
3.) After following the second step a new pop up window will appear,select set up a wireless ad hoc network.
4.) Next pop up window will ask you to give your network a name and choose security options and here you have to give network a name and a security key and press the next button right hand side of the pop up window.
5.) After clicking on the next button.The network you created will be ready to use if you are connected to internet with any source.The pop up window will ask you for a option called Turn on Internet connection sharing,You have to click on that option and this step will convert your laptop or computer to a wifi hotspot.