Patching .init files

For Developers
1

I have created a package and I want to make a patch for an .init file which is located in ./files directory. I have followed a tutorial on the wiki but I cannot find the necessary file in build_dir. I am fairly new to openwrt.

openvpn-ubus/
├── files
│   ├── openvpn.init
│   └── openvpn-ubus.init
├── Makefile
├── README.md
└── src
    ├── Makefile
    └── src

Package makefile

include $(TOPDIR)/rules.mk

PKG_NAME:=openvpn-ubus
PKG_RELEASE:=1
PKG_VERSION:=1.0.0
PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)-$(PKG_VERSION)

include $(INCLUDE_DIR)/package.mk

define Package/openvpn-ubus
	SECTION:=utils
	CATEGORY:=Utilities
	TITLE:=openvpn-ubus
	DEPENDS:=+libubus +libubox +libblobmsg-json +libuci +libargp
endef

define Package/openvpn-ubus/description
	OpenVPN ubus management system
endef

define Package/openvpn-ubus/install
	$(INSTALL_DIR) $(1)/usr/bin
	$(INSTALL_DIR) $(1)/etc/init.d
	$(INSTALL_BIN) $(PKG_BUILD_DIR)/openvpn-ubus $(1)/usr/bin/openvpn-ubus
	$(INSTALL_BIN) ./files/openvpn.init $(1)/etc/init.d/openvpn
	$(INSTALL_BIN) ./files/openvpn-ubus.init $(1)/etc/init.d/openvpn-ubus
endef

$(eval $(call BuildPackage,openvpn-ubus))
2

Have you select the package with make menuconfig ?
Have you build the package itself ?

If you want to make a patch, it will need some source to patch from...
A patch is only a modification of sources.

Your package look more a replacement or an add-on ?
A patch will be useful if you want to modify an already existing package or apply specific modification on a source, that you want to package.