Here is a guided meditation meant to serve as an introduction to the foundations of vipassana meditation. It's about 17 minutes long.
I sometimes feel that mindfulness practice has been done a great disservice by some of the ways it's been "marketed" to the west.
One common misconception about mindfulness, is that it's like a spa experience and that it's all about relaxation and feeling wonderful all the time. This is not accurate. It is true that in the long run, mindfulness will help you feel more relaxed and less stressed, those are extra benefits, rather than being the supreme goal of practice.
Mindfulness practice is about waking up to what is really going on, developing an awakened mind, not clouded by delusion. As Joseph Goldstein puts it:
The true nature of mind is bodhicitta — empty, radiant, and responsive to the world around us. This is not a pie-in-the-sky, inaccessible state. This state is here right now, yet often obscured by the egos habit of craving and aversion. Mindfulness is a process of lifting the veil as we relax the mind and begin to experience the freedom that is our natural state.