Two-Track Recording Advice, please

Here is my current set up:

Rode NT4 stereo mic

Fostex Fr2 LE high-quality digital recorder

Software: Wavelab Essential 6

I like the set up, and have used it for 8 CDs for banjo or ukulele books, but each time I have only needed to record one stereo track. I chose Wavelab Essential 6 for its high-quality, knowing it only allows one stereo track. However, my next project will require two instruments played by me. So, advice please on what I need to do to get two tracks. I downloaded Audacity, but it was too complicated for my non-techy brain. I want a simple, 16/44.1 wav recording, no fancy stuff :-) 

I did think of upgrading my Wavelab to a multitrack version, but it is expensive.