Most prominent teachers like Jon Kabat-Zinn, Sharon Salzberg, Jack Kornfield have talks on You Tube. Simply type their name and "guided meditation". on Topics, click on Meditation and also Mindfulness Meditation to hear several talks. Dharmaseed has  thousands of talks by hundreds of teachers. For first-time users, we recommend typing the name of a teacher and then listening to a talk whose title draws you. Though there is no charge, this site is funded by donations from users. This organization has many books and talks, most of which can be downloaded free.