Update README.md

Author: TheEnderek0

README.md

@@ -1,2 +1,20 @@
 # PyCaptionCompiler
 A rewritten caption compiler for Source File games in Python
+
+### Run with -h to get information on how to use this program.
+
+## This repository is also houses the main library.
+This library is used to compile captions natively in Python without calling a separate executable. In order to use this library you have to install it via pip, or add it to requirements.txt:
+`pip install git+https://github.com/Project-Collapse-Studios/PyCaptionCompiler.git`
+
+Then you can use this library as such:
+```py
+from pycaptioncompiler import Subtitles # Subtitles is the compiler class
+
+subs = Subtitles.from_path("C:/path/to/file/file.txt") # Will open the file and handle encoding, this is the recommended option
+subs = Subtitles.from_file(file) # An already opened file
+subs = Subtitles.from_keyvalues(<srctools.KeyValues>) # From an already parsed file with srctools.KeyValues
+
+with open("C:/subtitles_out.dat", "wb") as f:
+    f.write(subs.serialize()) # Calling serialize actually compiles the file and serializes it, returning it.
+```