I need to fill out forms online using adobe, but I do not know how to fill in the blanks. I have seen it done. How do I do this?

Adobe makes several software products. Please specify which product and version you are using if you require further assistance.

With the free Adobe PDF reader you can just click on the blank and type the text you wish to enter. Some forms might even have check boxes (just click to toggle the check mark). The availability of which fields you can modify and what you can do with the filled in form (save to disk, print etc) are options under the control of whoever originally created the PDF form.

See if this can help out

PDFfiller lets you fill PDF Forms on-line
https://www.pdffiller.com/index.php