Help with installation and setup

Greetings

I’m having some issues because i need to install the self-hosting invoice and make some changes or add mocules for use in my country, like use the currency from my country (honduran lempiras), also that the invoice numeration can be manage, for example start number and finish number for every month or date.
Also the best way to create the modules is there a manual, documentation or examples for the modules?
how is the best way to change the code and kept it without be affect by the new updates?

You’d need to create the feature as module for it not to be affected by updates.

This the only documentation we have:
http://docs.invoiceninja.com/en/latest/custom_modules.html

If you need help from a developer you can submit a request here:
https://www.thedevelopers.ro/customisation-request-invoiceninja/