Professionally? Yes, you need to know about aromatherapy before you use it, especially before you use it on someone else! Essential oils might seem harmless, but not all of them are. Some can cause burn-like rashes, some are photo-sensitizing (meaning, application before going out into the sun could cause a rash), some are sensitizing (meaning, you could use them for a while and be fine and then all of a sudden have a severe reaction to them), some are irritating to mucous membranes, some you can only use a tiny amount of, etc. There is a lot you need to know before you treat someone else, and it would be completely irresponsible to go into it blindly.
If, on the other hand, you just want to make a simple blend for yourself or someone you're close to, to use in something like an oil burner, then there are several books and websites out there for beginning aromatherapy.
You don't need any "deluxe equipment", just essential oils, something to dilute them with (carrier oil, alcohol, witch hazel, water, etc depending on what you're using them for).
Valerie Ann Worwood wrote a couple of books that I think are good beginning books for aromatherapy. You could also check this website: http://www.naha.org/ for some information and links to other sites.