this is advisable!
The adventure included in the boxed 5e "Starter Set"--the Lost Mine of Phandelver--is for you. In fact, the whole starter set is designed with you in mind. The rulebook is a coherent subset of the PHB (and thus simpler to wrap your heads around), the pregenerated characters' sheets nicely explain features, and the adventure has lots of notes to the DM. (Things like: in the next encounter surprise may be a factor; be sure to review the surprise rules on p.xx.)
On a personal note, I'd not played since the 80's and had never GMed when I picked the starter set up and got three other complete newbies to try it. At lunch the other day one of the group asked about starting up a third concurrent campaign so that we-all (and the half-dozen other newbs who've joined us) can 'get our fix.' the starter set works!
Then, while you're GMing or playing, keep a running tally of things to ask about here or in chat. At the beginning of each session you can go over all the questions, and you'll all learn together.
