Although DaVinci Resolve and Fairlight are designed for visual editing, as a free download the software offers a plethora of functionality and can be used on both Mac and Windows. Fairlight has a wide range of tools and effects and can offer an excellent introduction into both sound design and visual editing. It is particularly useful for podcasting as it offers such a wider range of tools. Below I have given some useful links into some online tutorials to get you started. You can download the free software from this link.
As an introduction to DaVinci I recommend starting with this tutorial below. It’s quite fast moving but it gives you a good overview of where to start.
This clip goes a little further by looking into editing and mixing with a good explanation and demonstration of vocal restoration, compression and equalisation. The video below goes into detail about some of effects available to you as part of the free download.
Blackmagic’s YouTube channel offers a good range of further tutorials which start at introductory level (below) and go much deeper. Although these concentrate on audio and visual they do offer some further insight into the deep functionality offered by the software.