Oh, oh, oh!!! I know the answer, in simply way. That's what the bike shop owner spent so much time explaining and having me practice. LOL!!! The way he simplified it, it just suddenly clicked in my head. I'm no longer scared of my 21-speed. However, I'm not sure the Raleigh bikes have the twist controls. Let me try to explain it, in my simple terms, meaning, my understanding.

My normal riding is in 2nd on the front which is my left control and 3rd or 4th on my rear which is on my right control. When I get to an incline, I just start switching my right up to a higher number (up to that 7 on my right) that maintains my cadence. If I start to hear a clicking sound, it's time to change the front gear (the one on the left). I can go either up or down and it won't hurt my derailleur, as long as I'm still pedaling. Well I haven't had to go into 3rd yet.

That's my very simple basic understanding. It works for me. Bottomline was, move the gears but ride where I am comfortable. Of course, I'm suppose to remember the "Don't do list" which includes pedaling backwards while trying to change gears.

I'm gonna suggest you go back to your LBS and ask questions. If they want your business, they will work with you and explain things to your understanding. I'm sure that bike shop really appreciated your business but anyone can sell a bike. What they really want is your return business, a loyal customer. Now, make them work for your business.