Recommended software for absolute beginners:
Audacity - free, open-sourced digital audio workstation with an intuitive, beginner-friendly design.
ClipChamp - freemium, in-browser video editor from Microsoft with basic editing tools with the option to export in 1080p
Soundtrap - freemium, in-browser audio editor that allows for collaboration among peers.
Recommended software for intermediates:
DaVinci Resolve - professional video editing software with a downloadable free version
REAPER - affordable, highly customizable digital audio workstation that offers a MIDI sequencer, VST compatibility, and is still fully usable after the 60 day free-trial has expired.
BBC Sound Effects Library - The British Broadcasting Channel has made available decades of professional-quality sound effects and recordings.
Freesound - The largest royalty-free sound effect library on the internet. All you will need is to set up an account.
Pixabay - Royalty-Free stock photos and music.