PDF is a file format that allows text (including fonts) and images to be embedded into a non-editable document. This file format is great for documents that you do not want changed or that you want to make sure anyone can open.
There are multiple ways that you can convert your non-PDF documents (such as Word files and Excel spreadsheets) into PDFs.

Using Microsoft Office 2007 or 2010
If you have Microsoft Office 2010, you can easily save documents as PDFs in Word, Excel, and other programs by going to File > Save As > Adobe PDF. (In Office 2007, you an also look for the Acrobat tab on the ribbon and click Create PDF.) Simply save the PDF with the name and location you want it to have and the PDF will generate.

Using CutePDF
CutePDF is one of many free programs that allow you to convert documents by "printing" them. You can download CutePDF online at http://www.cutepdf.com. Install the program that you downloaded. Now, when you go to print a document, in the list of printers you can print to, you’ll see one called CutePDF Writer. Select it, click OK, and then save your PDF in the right location.

Using Adobe Acrobat Professional
If you have Acrobat Professional (not the same thing as the free Adobe Reader), you can create PDFs by going to File >Create PDF > From File (or Multiple Files). You can also use Adobe Acrobat to combine multiple PDFs into one PDF, create PDF forms for online use, and more.