OK so there are a lot of ways to do "Sun Salutations" so don't worry if you are confused. To start- If you believe everything you read on Wikipedia- Sun Salutations originated in the 9th century through the Hatha Yoga Tradition (more about Hatha Yoga here). In the United States the Sun Salutations can be morphed into any series of poses that use plank- low plank- upward dog- downward dog as a transition to flow through different poses such as the warrior I, warrior II or other such standing postures.
Are you confused? What I like to tell my students is that Sun Salutations is a full body yoga exercise in which the practitioner flows from one pose to the next by connecting the movement to the breath. For instance- when you start at the top of your mat, you will take your first movement by reaching the arms up overhead. As you reach the arms upward, you will take a full inhale- matching the movement to the breath. Next, you will bend forward, exhaling the breath out as you fold. The movement continues- inhale and step back into plank position- exhale lower- inhale lift up for upward dog- exhale into downward dog and so on.
Sun Salutations can be a great way to build a home practice because it gives you a foundation to work with- and you can insert any sort of standing postures into the flow. Here is a simple flow that I like to do in the mornings (go easy on yourself at first...especially if your body has just gotten out of bed and is just starting to loosen up).
Here's a graphic for you to use to get started... or click here for my easy vinyasa yoga video