Your Tascam should do exactly that - plug in a mic and/or an instrument lead, record and play it back through headphones. You can record one or two tracks simultaneously, and up to 4 tracks in total.

If you want to be able to play the track on other equipment, you can then mix down the multi-track recording to stereo by connecting it to a normal cassette player, or better still to your computer where you can record it using something like Audacity , which is free audio recording and editing software.