Using internal mic on imac for online language lab

[cucuzzasquash]

I've been trying to figure out a way to use the internal mic on my imac, running os x, version 10.6.8 to input speech on the Pearson myspanishlab website. To no avail. Is this possible?

Also, if not possible, can I plug a regular ol' mic into my computer, or does it need to be a usb mic?

Thanks!