You have to complete the id3 tags of songs. Just follow below steps to do that.
If you want to edit ID3 tags with iTunes, the following steps will guide you on how to complete this task in details.
1. Run iTunes and find the song which you would like to edit its information by click on it. Or you can choose multiple songs at the same for editing.
2. When the songs that you would like to edit have been selected, you can refer to the steps as below:
I.Enter the "File" menu and choose "Get Info".
II.Choose "Command + I" on the keyboard of Mac or select "Control + I" on the keyboard of computer.
III.Hold down the option "Control" while you are clicking, or just have right click.
3. No matter which method you have chosen, the window of "Get Info" will pop up, where all the metadata of the song will be listed.
You are allowed to edit the information of the selected songs, which is known as ID3 tags.
Something about ID3 tags editing must be known as below:
1. The tab about "Details" which is also called Info in the older version is the place where the info of iTunes song is edited. The information including title, artist, year, album and more can be edited here. You just need to click on the fields which you need to add or edit, then the information will be changed by your words entering.
2. You can find album art of the song in the "Artwork" tabs. You can click on the button "Add Artwork" and choose images from your hard drive to add new art to the song. Also, the built-in tool of album art can be used to add art to the songs or album automatically.
3. The lyrics of the song are listed in the Lyrics tab. Taking down the lyrics automatically is the function in the new version of iTunes. While the lyrics must be copied and pasted to this field in the older versions of iTunes. Additionally, the built-in lyrics can be overridden by clicking on the option "Custom lyrics" to your own lyrics.
4. The song's volume can be controlled in the "Options" tab. Through the automatic equalizer setting, you can determine the beginning time and the ending time of the song. Choose the "Skip" option in the shuffling box so that the song can be prevented to show up in next or in the shuffle playback.
5. In the "Sorting" tab, you can see how the song, the artist and the album are shown in iTunes library after sorting out. For instance, a guest star may be included in the Artist ID3 tag of the song. This would be displayed as a separate part in iTunes. If the artist and the album name are added to the fields of "Sort Artist" and "Sort Album", all songs will be listed together in one album view and you don't need to change the ID3 tags permanently.
6. When choosing the "File" tab, you can see the information including song time, file type and bit rate and more are listed here. This is a new option in iTunes 12.
7. More song information can be added via moving the arrow key which locates on the left bottom of the iTunes 12 window.
8. The Video tab can only be applied to edit the video tags in iTunes library. The episodes from the same season can be put together in this field.
9. When all the editing is completed, you can save them by clicking on "OK" button on the bottom of the iTunes window.
For more methods, check: How to Edit ID3 Tags in iTunes