I have a 2005 honda civic, and i have a question about adding freon to it?

so my civic is blowing hot air when i turn on the AC, its the first car i have ever owned and dont know much about it, i actually had to ask why my AC isnt working and then discovered what freon is. so my question is what kind of freon do i add to it, and how do i add it.and also how much do i add, i see most of them come in cans of 12 oz. should i get more than one of those, or is 12 oz alot?

thanks for the help in advance :)