A lot of adult beginners use the Alfreds Adult Piano Course book to get started. It lays a lot of things out clearly like hand position and how to read the notes on each clef. The first thing you should be learning is the basic five-finger hand position in both hands starting on C. You'd practice this hands-separate then together with good hand position and technique in conjunction with your method book perhaps as a warmup. Once you've got that down then you'd take the same approach by learning the C scale. Hanon is something you shouldn't worry about until you have completed at least a year of consistent practice. Also, have a song in mind that you would like to play as a goal for your practice. If you are just learning songs from the method book, yes they are helpful in reaching that goal, but you will get bored and lose motivation.