I have no idea how to record MIDI using my electronicdrumkit

I tried this a few years ago, and just couldn’t get it to work. Then my friend suddenly noticed, that I can just use a guitar cord and just plug it in. I then used it a few years like that. But now I want to make my own sound, but now matter how hard I try to google, read, download, watch on youtube, I just CAN’T get it to work… My electronic drum kit is Yamaha’s DTXplorer (which has MIDI out, but no MIDI in [not sure if that matters or not]. My audio interface is Tascam US-1641. I have Cubase LE 5. The wire I use to connect these is “M-Audio” and it has 3 heads, MIDI in, MIDI out and a USB head.
My computer only recognizes the wire, and the lights go on on the wire only if I plug in the USB head to my PC (Windows XP Home Edition).
So what I do is I create a MIDI track, then try all combinations on Input and Output Routings, but nothing happens. Then I create an Instrumental Track. I do the same, try all Instrumental Routings, and put the DigiDrum Pro on the instrument option, and still nothing happens. Do I need to download something else? Do something else? Can I get this stuff for free? I just want to record my own drum sounds, so that they’re also mapped correctly on each pad on the electronic drum kit. I mean that’s such a simple thing, it shouldn’t cost anything, right? If it does, where can I buy the most simple and effective one for a cheap price (with nothing else added to it, it shouldn’t be that costy, right???).
If people can’t answer this here, could someone suggest a place where I could get an answer? Thank you.

You connect a MIDI cable to the MIDI Out of your DTXplorer, then connect the other end of the cable to the MIDI In on your Tascam US-1641. In Cubase you then add a new Instrument Track and load up whatever VST Drum instrument you want to use. Depending on the instrument you choose, you might have to assign each part of your DTXplorer to the various parts of the instrument. You should be able to easily find tips on doing that on YouTube or in the manual for the instrument.