Image Cutting
Most likely, you need to apply images and pictures to add beauty on your web page. However, images come in different ways. You need to unify them all under one theme. You need to edit, adjust, and format these pictures first and come up with better ones. This process is called Image Cutting. There are various sites that offer free image cutting or editing. Other sites have downloadable software that can help you more on your work like Photoshop. You can upload your own pictures or you can make and come up with your own to cut it up into HTML or CSS from PSD.
It is highly recommended that you slice pictures into small segments if you are planning to come up with one image. This can become really complicated so it is best if you refer to http://www.garysimon.net/webdesign_tutorial/3 for thorough discussion on image cutting and get pieces of advice, as well.