Was asked to sell an image

Hi everyone,
I was contacted by a company that wants to buy one of my images to be used in their internal campaign. I have never sold an image before, therefore I am all confused and need your help.What are the price ranges ? What kind of contract would I need? Is there a resource i can find contract templates I could use? Any conditions I should mention to them?
Like I said this is all so new for me and I have no clue even where to start.. Pls help!

I swear there are five of these threads every week. That being said, your first step is to know exactly how they will be using your image. That dictates price. Is it a one-time use? Will it be used for a longer period of time? These are all things that need to be known first before you can start talking money.