If you're talking about your current situation (and are not using a full sentence), you should use present continuous (verb+ing). This is done as a response to questions (Ex: A: "What are you doing?" B: "(I am) Thinking about..."), as well on places like Facebook. If you say "live a new lifestyle" as a full sentence, it will always mean the imperative. If you write that on Facebook or Q-Zone, people will think you're telling them what to do.

Your question really needs correction. Please pay attention to the spelling, at least. - I'm just wondering whether "live a new lifestyle" or "living a new lifestyle" is right? Giving another example, if I write them on my facebook or q-zone, which one is right? Well, you need a full sentence first. I'll give some examples. "Live a new lifestlye." This is basically a command. Maybe you would see this in an advert. "I would like to live a new lifestyle." You are thinking of a new lifestyle. "I am living a new lifestyle." Your current situation. "I enjoy living a new lifestyle." The "living..." part works as a noun here. "I'm looking forward to living a new lifestyle." You have your plans and it's going to happen. Like the last sentence, "living..." works as a noun in this context. If it's the caption of a photo, or a status update, then "living a new lifestyle" is correct.

Your questions were blurred. Try to make them clear by giving the complete of the sentence and not a chunk of.