How to additional shipping methods in magento ?
currently there are methods like Flat rate ,Table rates , Free shipping , UPS etc...
here is a nice tutorial on how to create a shipping method.
Or this one from Inchoo.
Basically you have to follow the standards presented in those tutorials and all your logic goes into the collectRates
method of the shipping model.
There you can calculate the costs of your shipping based on the values you receive in the $request
parameter and decide if the method is available or not and set a price to it.
Here's another link also for Magento 2 tutorial on how to create custom shipping method.