Bleeds are when you want an image or graphics to print to the edge of the page.
You need to make your artwork bigger than the final size.
Because every print does not print in the exact same positions, you may get void areas where the paper show unprinted if you don’t add bleeds.
With programs such as Illustrator and Indesign it is easy because they have bleed options. You can enter the bleed setting when you create the file or edit the page setup as well as when you save or export to PDF. Generally the bleeds should be set to 1/8″ and any text or important parts of an image need to be at least 1/8″ from the trimmed edge for flat work an 1/4″ for booklets.
Many people use Photoshop or similar editors that are not designed for print production. Although you can get very a creative layouts they do not have support for bleeds, so you can make the page size 1/4″ bigger in each direction (1/8″ on all sides) and keep text and important parts of the photos at lease 1/4″ from the edge of the page.
Adobe has created a collection of programs for the creation of both digital and ready to print. Each of the programs specialize in different areas of the design process. For the best results it is good to use the programs that are best suited for you needs, and frequently it is best to use more than one program to complete your project.
Although Adobe is the industry standard, there are other programs available you should do your research and pick the one that suits your needs best.
And although we can not provide tutorials for setting up you designs we are willing to try and answer any questions you have file setting and printing requirements. You can find our contact info here.