If you have a pdf file and wanted to make minor changes to it, the only way possible is to use pdf writer. This way is not always plausible as the software is expensive. There is a free alternative to editing pdf files using Google docs which is illustrated below. The only requirement to using Google docs is to have a Gmail account (if you do not have one, it is about time to create one).
Step 1: Go to Google Docs
Navigate to http://drive.google.com. If you are logged into your Gmail account, it logs you automatically into Google docs; else, just sign in.
Step 2: Upload your pdf file
From the menu, click on New > File Upload. This will bring up a dialog to select the pdf file on your computer. Browse to the location where the pdf is located and click OK.
Step 3: Open with Google Docs
After the upload is complete the file can be found in the My Drive Folder. Right click on the pdf file that was uploaded and select open with > Google Docs
Step 4: Edit the Pdf
This is the tricky part that most people miss. As shown in the screenshot below, Google Docs will present both the picture version (pdf pages as pictures which you CANNOT edit) and the editable text version both below one another. Scroll down to the editable text. Edit the pdf to your liking and delete the pictures part of the document.
Step 5: Download your edited PDF file
Once you have edited the file. Choose File > Download As > Pdf
Note that there are several formats that you can download the file. You can also download it as a Microsoft Word document and then edit the file.
Resources: If you need a free pdf to Microsoft doc conversion then this application comes to your rescue. PDF to Word.