I have a 5.1 Home Cinema system that I want connect my laptop but I do not know how to do it...
The fact that a laptop manages 5.1 or not does not change anything, since in any case you have only stereo output.
Look over your 5.1 system if there is a stereo> 5.1 transformation module.
Personal opinion: A 5.1 does you any good for a laptop, since the rendering will not be a "True 5.1" sound.
At the the limit a 2.1 sound system can be useful, but beyond that, it is not worth spending money buying an external soundcard with 5.1 output.