You have chosen your cast from their audition files, you've emailed the script to them all, and you've received the actors' lines.
It's time to start mixing.
Different mixers/producers have different ways of working, but for the purposes of this, let's use the 'numbered script' approach.
When the script is finalised, every character's line is numbered in order from 001 upwards. The actors will then record the lines and send them as separate mp3 files (.wav files are higher quality but are much, much bigger, so can be trickier to send and store if you're doing a lot of mixing. 128mbps is standard CD quality, but 192mbps is better quality again, and so many people recommend asking their actors for files of 128 or 192mbps, 44100hz).
You then process the clips, reducing their background noise, possibly evening up volumes or using EQ to make the actors' recording environments sound as similar as possible. You can also choose fx and music in advance. You now have all the parts you need. Now comes the piecing together of all the elements.
Most Digital Audio Workstations (DAWs) have horizontal staves onto which you can click and drag clips, as if they are musical notes on a stave.
Just like the mechanism of a barrel organ, the cursor travels left to right and plays the clips as it comes along to them. So moving clips to the left makes them play earlier in the mix, and to the right, later.
If you put any clips parallel on their staves, those clips will play simultaneously as the cursor passes over them all, rather like chords on that barrel organ.
The screenshot is an annotated scene from Der Tickentocker, to give an example overview of a DAW in action, and how a finished scene may look.
The DAW used here is Adobe Audition 3.0, but there are a huge range of DAWs. Free ones include Audacity and Ardour. Read an article on creating audio drama in Audacity here.
Download or stream Der Tickentocker to follow along with the screenshot below here. Happy experimenting!