You turn each IRS to NAV as you are doing, but you need to enter your departure and arrival airport codes into the FMS and then press the FMS soft key next to “ALIGN IRS”.
Depending on how you have it set up, the IRS alignment might be instant, fast or realistic in the time it takes to align. You can select how you want that to be via the Settings tab on the EFB.
See this screenshot, on the INIT page, you enter your two airports. You can see I have KPRB/KLAX entered in the top right. Then you can see that ALIGN IRS is next to the 4th softkey on the right. Press that and the IRS alignment process will begin:
See the second row on the EFB’s Settings page to set the IRS Alignment time:
