I have a fresh install of tmux with no custom config and I'm completely lost

After remembering that the default prefix is Ctrl-b, I'm able to do a few things

I need to start pulling pieces over from this tmux.conf file https://github.com/hashrocket/dotmatrix/blob/master/.tmux.conf

First, I need to enable the mouse so that I can:
- click between panes
- use the mouse to resize panes
https://github.com/hashrocket/dotmatrix/blob/master/.tmux.conf#L45

What should have been first: switching the prefix from Ctrl-b to Ctrl-z. I have too much muscle memory invested here.

Plus, Ctrl-z is a more comfortable combination on qwerty.
https://github.com/jbranchaud/til/blob/master/tmux/change-the-default-prefix-key.md

Binding hjkl to the pane navigation commands makes it more natural (for a Vim user) to navigate between panes. No need to reach for the arrow keys.

Tmux adds a delay to the escape key before processing it in case it is part of a binding. As a vim user this is a bit of an annoyance, esp. since I don't have any Esc–key-based keybindings.

So I set the escape-time to 0ms.

This is another convenience binding that is so ingrained in my muscle memory I cannot live without it.

By binding the Up-key to `resize-pane -Z`, I can quickly maximize and minimize the current pane.

Tmux has two key-modes: Emacs and Vi

These binding come into play for navigation, search, etc. when in Copy and Choose mode.

As a Vim user, I prefer what I know, hence vi keybindings.

This adds a couple copy-mode keybindings that you'd expect to be included when enabling Vi key-mode.

`v` will start a visual selection, once it covers the text you want to copy, you can hit `y` to yank the text into the system clipboard.