Your "net worth" is the amount of cash you would have left if you sold all your assets (car, house, furniture etc.) and paid off all your debts. In other words, net worth = assets - liabilities.
Enter the value of your assets and liabilities. If not sure, estimate the amount rather than leave 0. You can use the [Tab] key to move from input to input. You may click "Calc" as frequently as you like.
The percentage shown in each header is the percent of the total liabilities or total assets as appropriate. If "retirement assets" shows 15.7%, then "retirement assets" make up 15.7% of your total assets.
The "Personal Net Worth Summary" section is where you'll find your net worth. The liability percentage is the percentage of your liabilities to your assets. A result of say 75% simply means that your liabilities are 75% of your assets. The net worth percentage is the percentage of assets remaining after the liabilities are paid.