Funding can be obtained through a variety of methods. If you don't have any personal capital to invest, you can seek outside investors, hold fundraisers, or work towards saving enough money to fund your LLC.
There is no special way to fund a llc. The best way to do it is to write you business a check from your personal account if your are the one funding it. Make sure you put in the memo initial funding, and write it in the books as so.