[Puffin]

I am a new user and have bought an Android tablet and installed MobileSheets but have no idea how to use this app.   I am a singer belonging to three separate choirs and need to understand how I can maintain musical pdf pieces for use in rehearsals when I need to make notes on the music.   I then need a way of pulling together the correct pieces in the correct order for use in a concert.  Sometimes a piece of music could be used by more than one choir.    I have already managed to load up some of my music from my computer using Google Drive.    How can I keep sheet music easily so that I can find it quickly in a choir rehearsal for example?    I need HELP PLEASE.