One website that makes creating QR codes very easy is http://createqrcode.appspot.com.
Once you go to the website you can copy and paste a website url into the text box (1) then click on "create qr code", and the code will be generated (2), or type or paste text into the box (3 , and then click on "create qr code", and the code is generated (4). It's as simple as that. Once your code is created, you can save it the same way you would save a photo from the website (right click on the image, and save as "name.png").
FIrefox and Google Chrome both have a tool to use to easily create qr codes as well. You can find more about those here: