Open the Editor (Cmd-E, Ctrl-E), click where the text belongs, then click into the Text field and type.

 

Click the arrow at the end of the text field for the texts the player understands, such as D.C. al Coda, D.S. al Coda, and repeat counts like 3x. The up and down arrows move text vertically. Type two slashes (//) to start a second line. Cmd-S (Ctrl-S) saves and Cmd-E (Ctrl-E) closes the Editor.

 

Some users write lyrics with the text tool. See the Lyrics thread on the Forums.

 

For the full guide, see Edit a song on the iReal Pro website.