Finding pictures to use
If you are going to work commercial on the internet it is important that you familiar yourself with copyright law. By not doing so you will not know what to do when people are stealing your content and what is worse, you might not know when you commit copy right violation that might end up costing your money or even get you sued.
It is good to assume everything off limits until you have been able to confirm that it is okay to use. It does not matter if content is not registered it is still copyrighted and protected. The area where copy right causes the most problems and where the most unintentional violations happens is in regards to images. Images are protected and the rights belong to whomever took the photo (Or whomever he sold the rights to) You can hence not simply Google to find an image and use it. You need to find public domain images or images that are otherwise expressively allowed to use in the way you want to use pictures.
If you have the budget to pay for the pictures than you have a lot of different options ranging from having images commissioned (expensive) or buying them from stock sites. Another option is taking the picture yourself. In that case you will own the copyright and no one else can use them.
If you do not have money to buy images you will have to look for free pictures that you are allowed to use. That can either be pictures that has been released for public use, pictures taken by a government agency or pictures taken more than 75 years ago. There are several good resources for finding pictures to use. One of the best is sxc.hu where you are able to find thousands of images that are available for you to use. (some of them with certain restrictions so read the terms for each image). sxc.hu is a very good place to start your search for images you can us. You should however know that it is not always possible to find free images to use and in those cases you will have to settle for not having a picture in your content or pay to get the rights to use a picture.