Burning again

Once i've burned something to a cd-r or DVD-r.... how do i go back and add more to it? it says it's re-writable but it won't let me.

at the moment i'm just using OS X finder to burn. it's served me well in the past... but if it can't do what i'm asking about here.... please let me know what i should be using. cos i'm wasting discs !!

maddock

CD-R or DVD-R are one-time recordable media.

For repeat sessions, you need CD-RW, or CD-RWR, similar with DVD.

you're right. my mistake. but i do have CD-RW discs. should the finder burning software recognize and open ended burn?