I have a Canon Power shot S3 . Can I use a Sigma AF-Mf zoom lens 100-300mm to it. If Yes, what type adapter to use.? I also have a 35-80mm canon lens. can this be used ? Thanks.

Your camera is a fixed lens compact model. You cannot fit other lenses to it unless they are specifically designed as supplementary lenses which screw onto the existing lens filter thread.

There are no adaptors you can safely use either, the only ones would be lens reversing rings which are used to mount lenses backwards for ultra close-up macrophotography, but the weight of the lenses you propose on the end of your existing lens would break your camera.

If you wish to use interchangeable lenses then you need to obtain an SLR or an interchangeable lens rangefinder camera.