Click on the desired form from the menu on the left. The file will open on your computer. Click in the yellow text box and enter your information. You can save a partially completed document and finish it later by choosing 'Save As...' from the file menu.

Choose 'Open' if you are given a choice between saving and opening the file.

Note: Some browsers block downloads. If this happens, click on the narrow box that appears below the address bar and choose the option that allows you to open (or download) the document.