lunge lesson

As, I am beginner i have not much idea that how can i train my horse perfectly. I was thinking to buy lunge lines but once my colleague told me that it can hurt my horse. Is it true or just a myth?

There are several instructors at my RS- I've only ever had one of them. I only started riding again in September after a 17-year absence (due to lack of money, lack of confidence, and being considerable fatter than I had once been). I'm now looking at getting a horse on working livery there. One...