[Plugin: Woocommerce] Change shipping price in checkout page

Hi there!
I’m trying to create a plugin for Woocoomerce (WC_Shipping_Method), that allows to add a shipping method.
To calculate the cost of shipping, I need data that the customer will type in the checkout, I am able to do the calculation but do not know how I can allocate the cost at checkout.
If I use a custom fee if I can do it, but what I’d like to do is update the value of my shipping method.