Haha, I can't believe MIDI has been around for almost 30 years. And it is still good today!
You will need a MIDI controller of some kind and really an inexpensive one will work and just fool around with that to see what you like. I'm not a musician but like to screw around with sounds but a good tip would be to go to a local music shop and ask them about MIDI and tell what you want to do. If they try to start and sell you something really expensive walk away.
For that matter, you might find a cheap keyboard at a thrift store that might do the trick. That is where I found mine years ago.