How to add layer of mirror on object

In SOlidWorks, Appearences are chosen for the entire geometry, are face, a feature, a body or a document. There are a few ways you could accomplish what I interpret you question is about:
1-Picking individual faces instead of the whole model
2-Finding something that will look like a mirror

1-Try clicking on your model. It the entire model lights up, it means it is made from a single surface (like a sphere) and then you might be in a pickle. If not, you can pick the desired faces you want to make a mirror off, (hold shift for multiple faces), then right-click on one of the faces and choose the colorfull ball. You may also pick features from the Feature Manager Tree and changes their appearences.
If you are not in luck and your model is one surface, you may try to make a construction plane in front of the place where you want your mirror, draw the outline of what you want mirrorized, and use that sketch with Insert>Curve>Split Line... This function will split your surface into two surfaces: a part which boundary is your sketch, and the rest of the surface. You can now select that part of your surface seperately, and make it your mirror. If you are looking for a coating, you might need to make a separate body on that part of your model. I am not aware of a better way than. :(

2-For the desired effect, you may try 'Chrome plated'. This will make the chosen faces as reflective as a mirror. You can also choose Clear Glass and changes its transparancy to 0%. This will turn the glass into a mirror as well.
If you are just looking to make your model red, but so shiniy that you can use it as a mirror, you may want to try the Painted>Car appearance and set it to 'Shiny' (That option is just above the little color pick panel, and below the two colors it will reflect).

I hope your answer is somewhere in this wall of words...

transparancy might work but i cant find it anywhere
i went to edit color but there is no bar to trag transparancy to 0%

There is though... It is situated below the Color pull-down menu, in a pull-down menu called Optical Properties. And it is a slider from 0% to 100% alright... ;)
If it really is not there, you might have a very old or very new OR very weird version of SOlidWorks... :s