How to use a Can Opener???

I have seen a Can Opener and have used canned food, but never been curious to use it, I thought using one would be a very simple task but it proved different... I always have a notion that Canned Food was not very healthy but in this quick world there is no other resort, rather to get used to canned food... I prefer Tomatoes and Corn Kernel and nothing more, in can but not always... I have never opened a can, ten days back I wanted to make a dish with Corn Kernels and I tried using the Can Opener but uhhh ah... I tried all kindsa tricks that I could but the can was left with dents and marks and nothing more... Luckily he came home at the right time to rescue me oops nope rescue the can and the opener... Then I realized that opening cans were the most easiest thing and any one can learn it... There are 2 wheels on the Can Opener, the sharp one rests on the can, which slids thru the can top, the wedged wheels is on the side... I have seen many Can Openers that are labelled for left handers too... No idea how those work....