Crash68 pretty much said everything that needed to be said.
A/C repair is not DIY friendly, there's so much more that goes into it than just hooking up a can. Not to mention most of those cans contain stop leak which can clog up the system. Most shops won't even touch your car if they find out you put stop leak in the system, as it will also mess up their machines.
At the very minimum you need a set of manifold gauges and a vacuum pump. You should never just add refrigerant. The only way to know for sure if it's properly charged is to recover the entire system. A/C is charged by weight, not pressure.
So as others said, take it to a shop and hope you didn't cause any damage.
