@wilsongangmei
You get a tax ID number for your LLC from the IRS web site for free.
https://www.irs.gov/businesses/small-businesses-self-employed/get-an-employer-identification-number
LLCs are created under state laws, so the benefits of having an LLC, and the cost and other requirements, vary from state to state. If you want to organize your business as an LLC, you need to decide which state you want to organize in (usually the state where you live, or the state where you will be doing most of the business activities) and then contact an attorney or other expert in that state.
