Step 1: Enable your Action Bars
Game Menu > Interface > Action Bars > Select all action bars
This will display all possible action bars so you can start binding them. If you select the option "Lock action bars" this will prevent you from click and drag a bind by accident. If you want to change something with this option enabled, you need press shift+click and then drag a bind away.
Step 2: Keybinding Panel
Game Menu > Interface > Keybindings
This opens the keybinding panel. This is where the magic happens. I'm not going to go through every single section because that's just boring. The first section are your movement keys. You can change this section the way you want, but a highly don't recommend this because if you have been playing wow the way you have and you like it, then stick to it (WASD, maybe?). A bit bellow that you will find your "Action Bar Functions". Button 1-12 is your main action bar. You can also find special button bindings which are for vehicles and pet bindings. Even further bellow you will find "MultiActionBar Bindings". This section is for the additional action bars that we enabled in step 1.
Step 3: Start Binding!
Simple as that. Click on on whatever you want to change and press the binding you want to set it to. Remember that you can have modifier keys too! (shift, alt, ctrl)
Note: If you decide to bind something make sure that key is not currently occupied or you might have some confusion. For example if you want to bind C, and you currently have C for your character info panel then you have set a new bind for that (or leave it unbinded if that's what you want)