Surrah:

Peronsally I wouldn't use the phrase "I am new to the game". Saying this almost says to people that you don't know your class or you don't what threat means or how to manage agro or even how to 'get out of the fire'. Most players - even new ones, understand these concepts. So if your doing a quest or an instance with a group, I would state when you join them something like:
"Ahh, I have never done this isntance(or quest) before, so don't be afraid to yell out anything I might need to know"

Most people respond to this by typing in a sentence or two before a boss or a gauntlet area or a nasty pull just outlining anything important. This is helpful for you and at the same time, you have prepared them for the chance you might make a mistake.

Peronsally - I am always happy to give new players tips, or spend 30 seconds outlining a boss or even showing them where a quest mob is; as long as they ask and are polite. What I really really hate is people who put themselves in ques for an instance or raid and don't have the knowledge and often the gear to do that instance/raid. Most of these people know they don't but do it expecting to be carried. Its these type of people that turn older players away from helping the geniune new players.

S.