Well you don't need to format it. Direct-cd and in-cd (neros equivalent) are special program that let you use the cdrw like a floppy disk. However this is limited to data files. If you mean mp3s then thats ok but if you looking to make proper music cds then I'd recommend that you use nero's wizard (as you are a beginner).
Ps As you are making audio cds I'd better warn you that unless the hifi specifically sdays that it supports cdrw playback you won't be able to lisen to your disk in the hifi.
Ps As you are making audio cds I'd better warn you that unless the hifi specifically sdays that it supports cdrw playback you won't be able to lisen to your disk in the hifi.