Teaching online is similar to teaching face-to-face yet it also unique. Most online courses are asynchronous, meaning that faculty and learners access the course from different places, at different times. When teaching online, faculty must establish their online teaching presence, lay out clear expectations for all involved in the course, encourage student engagement and active learning, provide prompt and meaningful feedback, foster an atmosphere conducive to an online learning community, and much more.
A wonderful resource to learn more about the basics of teaching online is the public-domain course offered by the University of California Online.