Umali is probably not a native speaker and asking for help. Probably feeling like drowning.

Beginners need the correct text level to start. Good books provide the backbone or framework for the whole course. I really like the Lets Go book series, but a basic phonics workbook is necessary for alphabet and sounds, like UP & AWAY, printed by Oxford.
You have to test/show each book level to students individually and discover their English ability. Putting 14 year olds in a class with small kids is not a good formula but sometimes the older students are very protective and help the younger ones. Move kids up a level when you see they are underchallenged. The book is just a framework. The rest is up to you as class organizer.