Add URL ,CATALOG to be editted

hi guys threre is a question i want to add some field like URL ,CATALOG in mp3 tag how do i do this

i want to add this highlighted field in mp3 tag

To see exactly what fields are used for this data, try entering some test data there then open the files in mp3tag. Check the Extended Tag view to see the names of all fields that contain data, and find the test information you added. You can then use mp3tag to enter new data in these fields for any files you choose.

See the documentation on how to customize tag panel and file list:

To expand on MotleyG's reply:

From your screen shot it appears that IMP has abbreviated some tag names.
Mp3tag does not do that. So your CATALOG tag may be shown as CATALOGNUMBER in Mp3tag, as that is the correct term for ID3v2.3 (TXXX:CATALOGNUMBER).

Similarly your URL field may show as one of the six standard URL tag names for ID3v2.3.
The full list of tag names for ID3v2.3 is shown here:

Of course you can create custom fields simply named CATALOG or URL but I see no reason to do that when standard tag fields are available