Aegisub is the software we use.
I have a tutorial here that will help you get the software set up and go over some basic keybinds and techniques: https://youtu.be/B1XSXbi_ai4?si=G_bCZx8n6foPSKuM
And then we have a subbing discord channel and spreadsheet where we help each other out and keep track of what everyone is working on. Feel free to DM me if you'd like to join there ヽ(´ー`)ノ