Is your screen resolution at the recommended value?
You could open the Console view (Views>Console, or click the Console icon above the Track view) and insert the effect there.
Do you mean you want to add more measures to the song somewhere in the middle? Place the Now line where you want the space inserted and click Insert>Time/Measures at the top and select the amount you want inserted. This will split the track where the Now line is at and move the last part over to the right.
Does your media player play .wav files? Those are a lot larger than mp3s, though, so you may not want to use so much space on the player. If you do not have an mp3 encoder on your computer, there are many available for free on the internet. Export your song as a .wav to your folder of choice and then convert it to mp3 to load onto your player.