I need to know how to charge the air conditioner in my 2002 dodge ram. It's blowing hot air.

You need to find the low pressure side of the compressor and hook up the can of freon, with an adapter. Is the compressor cycling? You may have a bad compressor seal and the freon will leak out again.

This link will help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1864159

You should get it checked out, it may have a hole in it, causing it to not work.

I would bring it to a mechanic: I know what to do, but it is very hard to explain, sorry!

I am not sure it can be done, I had this problem once and the mechanic couldn't help me with much so I put my car on the local <a href="http://trucks.isuzu.com.au/">trucks for sale</a> list and got better truck, that's the easiest solution if you ask me and I am only speaking from my own experience.