Can I Connect computer to another computer wireless without router or access point

A computer to computer connection is called an Ad Hoc network. When your wireless adapter in your computer performs a discovery of nearby devices, it should also see other computers and wireless networking devices.

One of the options in your Wireless Software on your computer is to set up an Ad Hoc network. This is where you set up your computer to computer connection. Once this is done, you will then be able to share files providing that both computers are enabled for File and Printer Sharing.

How to connect my other computer

Please see Microsoft's documentation of setting up a ad-hoc network with Windows XP Windows XP: Set up a wireless network without a router