how can I insert the command "trill" in my music sheet?
Look at https://forum.noteworthycomposer.com/?topic=464 , https://forum.noteworthycomposer.com/?topic=43 or https://forum.noteworthycomposer.com/?topic=615 .
Instantly found with "Offline Forum", see http://www.noteworthysoftware.com/nwcforum/offline.htm ...
HTH,
Mad
The simple answer is use grace notes.
32nd notes is the best way to do trills, in my opinion.