The term guru is confined for the well-respected teachers who teach yoga. The title of a guru cannot be acquired by everyone and requires many years (often decades) of devotion and mastery of a skill. One of the most legendary gurus that are still alive today, is Sri Sri Ravi Shanker who was born in 1956 and is still present in his service towards the mankind.
There are various DVDs and online courses led by Sri Sri Ravi Shankar that you can buy off the internet. These courses tend to be very comprehensive and are targeted towards all levels of yogis.