Mp3 title

Question

When I upload my songs onto my e270... half of my songs are titled wrong or untitled at all. some songs don't have an artist and it makes it hard for me to search for a particular song on the player.I know that all the info that I need to change to fix the problem are on the summary properties of the file but I don't know how to change the fields. The only field that I can change is the title and sometimes nothing at all. I need help. How do you change the property summary of an mp3 file?