Here's some of the computer tools I use to make electronic backing / loops:
I had been using instrument samples and looping them through Cakewalk Studio program for a fair while manually. A few years back I came across the wonderful invention of 'Virtual Instrument Technology' which opened up a world to synths and 'natural' instruments. These gave opportunity for me to find and use sounds I could hear in my head but couldn't frustratingly put down through normal recording. Not only that, many kind people who invented these have given them out for free over the 'net, so being on a strict home budget where feeding the family comes first; I've been very grateful to have access to them.
A few years back an enigmatic software designer from the Netherlands named Bram Bos made a few great pieces of music sequencing software which I have used in much of my music. 'Tunafish' become my favourite because it was so well set out. Here are a few screen shots:
Drum track (photo)
Keyboard tracks (photo) with the option of using samplers or Vstis
So I would work out the chords and song on guitar and then spend hours working with what sort of backing track using this program and Cakewalk/Sonar LE (Digital Audio Workstation).
Watch this link to see it in action (from 2011)
Bram Bos (maker of Tunafish) vanished off the net a few years ago and his website went with him (to do more important things, I imagine) but I have a debt of gratitude for his work in making simple sequencers which were essential for me as a guitar player to make the backing music.
After getting Sonar LE, I found how to use VSTis fairly quickly and went for it.
Here is a more experimental tune I used guitar, sound samples, drum loops and VSTis to make. I specifically made this particular film clip (just using Microsoft Movie Maker) to show all the different VSTis as an example for a friend. As the clip goes along, I point out what I am using to make a particular sound. The majority of the VSTis are being used through Sonar LE which I used to make the song in this clip:
I also made this clip for a friend showing a more 'orchestrated' use for VSTis:
More on VSTs here: http://en.wikipedia.org/wiki/Virtual_Studio_Technology
VST 4 Free
Some paid many free great sounding instruments at DSK
And there are more of course...
I'm now experimenting with LMMS after not liking it earlier - they have updated it to a better quality free sequencer. More on LMMS later if it turns out as good as it is looking for basic home sequencing.