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.
I would consider loans and contributions because it's not classified as income. I would also keep in mind that loans are a form of debt that must be paid back.
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.
Write a check from your personal bank account to your LLC bank account. This money is counted as your original investment which QuickBooks or similar should classify as Owner's Equity.