Watermarking your photos
There are websites online that allow you to watermark your photos for free such as umarkonline and watermarquee. Creating your own lets you create one thats unique to you. If you're putting photos online and want to protect your rights to those images, the best way to protect digital photos is by watermarking them.
With a digital photo, a watermark is a faint logo or word(s) superimposed over the top of the photo. The idea of placing a watermark on your photos is to prevent others from trying to copy and use the photo without permission. Many websites use watermarks to show that a particular image is copyrighted, and it may not be copied and used elsewhere without the permission of the original website.
Former past president and club member, Don Komarechka, created this pdf document which shows a really simple and clear way to create a watermark
The Bottom Line
Ultimately you have to decide whether the process is worth your time and expense. Very few photographers need to place a watermark on every photo they upload to a social networking website. If it's a quick snapshot of your family or a photo from a recent vacation, chances are pretty high that no one will want to steal that photo for use elsewhere. But if you've taken the time to set up a high-end photo, investing a little more time in inserting a watermark may be a good idea. With the recent advances in Photoshop, its become easier for people to remove watermarks. Many use the watermark so others may more easily idenify their work, using it as a form of brand marketing. Just keep in mind that there is no real foolproof way for deterring people from stealing your work online (short of not posting photos) if they are really determined.