Add Makefile and instructions

Makefile

@@ -0,0 +1,19 @@
+.PHONY := builds finalize.romfs finalize_helper.firm clean 
+
+all: builds/finalize_helper.firm
+
+builds:
+	@[ -d builds ] || mkdir -p builds
+
+builds/finalize.romfs: builds
+	@3dstool -c -t romfs --romfs-dir finalize --file $@
+
+builds/finalize_helper.firm: builds/finalize.romfs
+	@cp finalize_helper.gm9 GodMode9/data/autorun.gm9
+	@$(MAKE) -C GodMode9 SCRIPT_RUNNER=1
+	@cp GodMode9/output/GodMode9.firm $@
+
+clean:
+	@rm -rf builds
+	@$(MAKE) -C GodMode9 clean
+	@rm GodMode9/data/autorun.gm9

README.md

@@ -38,6 +38,28 @@ Releases are tagged for reference (based on usage in the guide). **Releases in t
 
 `finalize_helper` is not necessary unless you intend to use the RomFS build.
 
+
+## Building
+
+You need the following tools installed on your computer:
+- [3dstool](https://github.com/dnasdw/3dstool/releases/latest)
+- [devkitARM](https://devkitpro.org/wiki/Getting_Started)
+    - devkitARM is only required if you are building the FIRM, which you are going to want to anyway
+    - Install the 3DS related packages
+
+Clone the repository via the following commands:
+```
+git clone https://github.com/hacks-guide/finalize --recurse-submodules
+cd finalize
+```
+
+And build:
+```
+make
+```
+
+The romfs and FIRM will be present in the `builds` directory.
+
 ## License
 
 TBD