Is your business an LLC or is it a sole proprietorship? It's nor clear whether you actually formed an LLC with your state government? Just saying it's an LLC on Form SS-4 does not create an LLC. You have to establish an LLC with the state. If you checked Yes in box 8a of Form SS-4 and you do not actually have an LLC, then your SS-4 is wrong.
As M-MTax said, a single-member LLC is disregarded for income tax purposes. If you have a single-member LLC you report your business as a sole proprietorship on Schedule C in your personal tax return, exactly the same as if you did not have an LLC. You can do that with TurboTax. When you posted your question you selected TurboTax Self Employed Online as the product, but that no longer exists. If you use TurboTax Online you have to use the Premium edition. If you use the desktop TurboTax software you could use any edition, but you would be strongly advised to use Home & Business (not TurboTax Business, which is a different product).
You continue to file your tax return after the end of each year, as you always do, just adding the business on Schedule C. If you have no sales or other business activity for the year, you have nothing to report, so you can file your tax return as if the business didn't exist.
Any net business income (i.e. profit) is taxable. If your net business income is more than $432 you would have to pay self-employment tax in addition to regular income tax. If the tax is going to be significant you might want to make quarterly estimated tax payments during the year, to avoid owing a large amount of tax at the end of the year, and possibly being penalized for not having paid enough tax during the year.
