Where do I begin if I want to create music using just a computer?

Hayden asked: This isn’t my profession or anything and I’m completely amateur, but sometimes I come up with tunes in my head that I’d like to save somewhere and work with. I don’t play an instrument but just want to experience with creating tunes with some sort of digital program. Does this sort of thing [...]

i want to create guitar tunes on computer without any other hardware. Can anyone suggest me some cool software

bro_duke asked: i want to create digital music on my computer, i donot want to learn or purchase real guitar. but i am looking for software which can create guitar sounds and tunes/rhythms. Can someone suggest me such softwares?