u know this better :)

Can I use a 6.1 or 7.1 channel receiver with 5 speakers. Suggest me folks.

Yes, you can. I am doing it.

I'm useing a 7.1 receiver with 6 speakers.

Thanks folks, me stupid, very new to Home Theatre thing. Soon may get some experience.

Since you are new to HT, if you use a receiver that supports 7.1 for 5 speakers only, the watts for the sixth and seventh channels are not completely lost but not entirely gained in the other channels either. All channels come from one power supply so, if your receiver is rated at 100 watts x 7 and you only configure it for 5.1 then you can expect the power to increase to possibly 120 watts x 5.