How to make a FreeLook camera

Hi! I am making a 3D version of "Rio de Janeiro", one of Brazil's cities. It's pretty fine, and i am almost done, but i have a little problem.

I am a beginner at scripting, and i don't know how to make a Camera control xD I wanted to do a camera like those that are used in strategy games. Something like use the mouse wheel to zoom in and out, move the camera using the keys and rotate the camera using the mouse itself.

I know that Unity does have the FreeLook camera, but it isn't the same thing. Actually, it's pretty the same, but i want something with more control. Could someone help me? Unfortunelly, my time is limited because i have to send it next week, and i am just horrible at scripting ;-;