My laptop is a Asus N55SF & the graphics card is a Nvidia Geforce GT555 M. How can I use 3D Vision?
Your laptop screen can't display 3d, so you need a 3d display device to connect it to. I addressed the topic quite extensively here: //www.makeuseof.com/tag/laptop-monitor-tv-3d-frequently-asked-questions/
While the graphics card should support 3D Vision neither the manual nor the ASUS website state that this model is capable to do it ~ therefor I'm not sure it will work at all.
As for using it you will need a display device with 120Hz and the 3D Vision glasses.