This page will show you what is needed for the size of the roster per team, starting line-ups on a weekly basis.
Each Team will have 19 players. You decide on which positions you want to hold.
For submitting the weekly line-ups you will need to start at least:
1 DL (DE or DT)
1 DB (CB or S)
1 flex between RB or WR
1 defensive flex for any defensive position
line ups can look like for offense: