If you've ever worked with music before then you might have seen a studio. If you haven't think 'a lot of equipment, wires to trip over and a big expense. You can rent them or build your own - either way you end up paying out a fortune. But untila while ago this was the only way to do things. You had no choice.
Then along came tools like GarageBand. I say like GarageBand because GarageBand is not exactly studio quality but you know what I mean. Digital music was born and a home computer (or laptop) can suddenly do the same thing an entire studio could. I'm sure the studios hate these tools now but they're certainly the future.
The software we work with (and suggest you use) is low cost but was designed to produce studio quality music without the need for an actual studio. Before you would need several rooms and a quickly depleating bank balance. Now you need a computer with internet access and a mouse. Friends of mine rented a studio for a while and played us some tracks they had spent well into three figures to produce.
A few hours on the laptop and I had the same track sound just as good, if not better. Some people treat digital music like it is cheating or somehow ruining "real" music. I let people argue with whatever they want but my philosophy is if it sounds good then what does it matter?
What you need for yourself can really depend. If this becomes something you really want to do you can slowly build yourself an actual studio and add whatever equipment and instruments you want. Yes, there is a lot you can add if you want and sure it gives you a lot of functionality. But the beauty of digital music production (well, one of them) is that you don't need all that cost to get started. In fact you can really go quite far without any of that. I started on the foot of my bed with a laptop which (as you might expect) made things a lot easier.
If you want to build yourself a home studio in the future you'll need to take a lot of things into account. You'll need sound proofing, proper acoustics, space and a lot of equipment. For now though if you're managing to read this page then you have everything you need to get started.
Ideally you'll have somewhere where you can practice frequently which can mean your own space or even just a pair of headphones. Personally I like working with a double monitor setup, a quality pair of headphones and a notepad sitting next to me at all times. But I started with my 10 year old laptop and a beat in my head.
And my personal pet peeve at the moment is that people will probably tell you that you need a Mac for this because everyone knows that music creation and editing is only done by Apple users. To hell with that I work with a GarageBand for Windows alternative and you will not see me on a Mac anytime soon.