There are many pre-designed certificates tat come with a template. All you need to do is add your text and print. Certificates can be purchased at office supply store and anywhere you buy printer paper.
If you want more control over the certificate, it is very easy to start from scratch. Look for thinner card stock or thicker paper. While looking for paper keep in mind the color combinations and frames you want to use.
What you need:
Each certificate should have these sections:
Layout. The entire certificate should be centered both vertically and horizontally. Start by inserting text boxes for each text item and word art depending on which software program you are using. Don't worry about placement until you have all the items on the screen.
Next, move the words "Awarded to:, to the center vertically and horizontally, then space the other items accordingly.
Graphics. Add a page boarder. Most software programs have many different types of boarders. You can change the colors and the width. You may also want to add a background image. This graphic should be almost a "washout", you should just be able to make out the design. It should also not be too busy, not have too many things going on in the picture. You can find many combinations of free graphics on the internet, these graphics can be used for personal or business as long as you will not be publishing them in book or on the internet.