To add bleed in a design, extend the background color, graphic, or image beyond the final trim edge of the page by .125″ (3mm).
Depending on the application used to create the design, this means your document height and width dimensions will be .25″ (6mm) larger than your final trim size. For instance, if the finished size is 8.5″ x 11″ then your document needs to be 8.75″ x11.25″. When setting up the document, you can create trim guides (trim marks) that show where the finished document will be cut.
Position all your bleed elements so they extended past your guides, all the way to the outside edge of the document. Remember, the extra .125″ will be cut off during the print finishing process.