youre not in a good place man... ive pretty much decided that it takes AT LEAST 3 mics to get any kind of quality sound. in order to record three mics, youll need an input system: an audio interface with at least 3 cable jacks. after you get mics and an interface, youll need software, but macs usually come with at least garage band, which to say the most, is usable.
on your budget, im not sure you can afford 2 more mics and an interface, assuming you already have garage band.
you CAN record with just one mic, but you will have quiet bass sound, and poor quality all around.
you will need an audio interface no matter what, though.
once you get mics, set one up hanging over your head (the overhead mic... good name, right?

), put one inside your bass (the best way to do this is with a port hole reso bass head, otherwise just put it close to the reso head), and then one mic under your floor tom pointing toward your snare.
plug them all in to the input system, and plug the input system into the computer. hit record.
you can run the mics through an amp to adjust recording levels and equalization, but you need a mixer/pa system for that, and you cant afford that. if you already have one, youre in luck.
anyway, if you decide to record with only one mic, then experiment with placing, just move it around until you get a sound you can live with. this way you will only need a single input interface, but its a good idea to get a better one anyway.
these are good mics, but theyll take most of your money:
Buy Shure SM58S Mic with Switch | Dynamic Microphones | Musician's Friend
hope this helps and good luck
butter