Wordpress - WooCommerce - Order create function?

Question

I am trying to create my first Wordpress plugin. I decide, to start with the most ****** process the checkout. Everything work well with overrided templates, but i want to write my own WooCommerce create order function (it's must needed for usage). How can i find, the exact function, what create the full order including (check customer exist or not, and the next step for payment.)

For example: if i create order with bank transfer, the status needed to set 'before payment', but the next page is thank you page. But if i choose Paylike payment method, the next step is order-pay (heres the paylike payment trigger), before thank you page show up.

I would really appreciate the help, because i can't find any function or reference in google what i looking for :(. Thx!