Camera and Mouse Movement

I am trying to make a top down game (basically a build your kingdom game, defense turrets, barracks, etc...) and I am not sure how I would go about making the movement. Because I want players to be able to click, hold, and drag the mouse to be able to move around the screen. I also want them to be able to zoom in, but not too much, same thing for zoom out. I am somewhat new to this and I am in the learning process. So also if someone could answer this and point me towards some tutorials that have to do with this that would be awesome.