You need an image? Then it's the best option to take out your camera ant take one yourself. Then you are the author and you should choose a license you want to release the image under. If you don't choose one it will be © Copyrighted by you until 70 years after your death. Nobody will be able to use it without your consent or without a license.
So you need an image of something else where you can't get so easily? Then you can try different sources. There are commercial stock image providers where you must pay for using the image. Using the image without license may result in legal action against you. On the other hand there might be images which are licensed for you to use for free under some conditions. Make sure you read, understand and obey those conditions. The conditions may be very differently, for instance that you pay roayties, that you are giving credits to the source or mention the licence it is under. Here are a few links:
Image search engines
- http://images.google.com
- http://www.picsearch.com
- http://tineye.com reverse image search
Commercial Stock Images
Images under creative commons and roalty free licenses
- http://commons.wikimedia.org
- http://unsplash.com/
- http://www.pixelio.de
- http://www.flickr.com/search/?l=commderiv search flickr for CC images