Question of the Week: How do you put a player on injured reserve?
Answer: On your team page, click the drop-down option in the Availability column and if the player is eligible, one of the options will be IR (vs. Bench for example). Choose that and click Save at the bottom.
To check if a player is IR eligible per your league’s rules, hover over or tap the player’s injury designation and a hover popup will tell you if they are eligible:
To check what your league’s minimum injury level is set to, go to the Rules page and hover over “IR” in the Rosters section — it will list out which levels are acceptable: