Alt tags for Featured Content & Features Slider

Help! A client is REALLY pushing me to do some edits and I can't figure out how to do them. On the home page, how can I add custom Alt tags to the images in the Featured Slider and the Featured Content? I have 3 slider images and 4 content images and they each need different Alt tags. The site is at: http://50.87.248.220/~trinivi3/ Thanks - Gina B