diff --git a/README.rst b/README.rst
index 52bd4d9..c80bc5f 100644
--- a/README.rst
+++ b/README.rst
@@ -2,11 +2,35 @@
 varST(var ➡️ reStructuredText)
 ==============================
 
-|pre-commit.ci status| |Documentation Status|
+|PyPI version| |pre-commit.ci status| |GitHub Workflow Status| |Documentation Status|
 
 Replace substitutions in rst files with variables.
 
+Installation
+------------
+
+.. code:: bash
+
+   $ pip install varst
+
+Usage
+-----
+
+.. code:: bash
+
+   $ varst [-i INPUT] [-o OUTPUT] [name=value ...]
+
+License
+-------
+
+`MIT
+License <https://github.com/junghoon-vans/varst/blob/main/LICENSE>`__
+
+
+.. |PyPI version| image:: https://img.shields.io/pypi/v/varst
+   :target: https://pypi.org/project/varst/
 .. |pre-commit.ci status| image:: https://results.pre-commit.ci/badge/github/junghoon-vans/varst/main.svg
    :target: https://results.pre-commit.ci/latest/github/junghoon-vans/varst/main
+.. |GitHub Workflow Status| image:: https://img.shields.io/github/workflow/status/junghoon-vans/varst/Upload%20Python%20Package
 .. |Documentation Status| image:: https://readthedocs.org/projects/varst/badge/?version=latest
     :target: https://varst.readthedocs.io/en/latest/?badge=latest
diff --git a/docs/source/varst.application.rst b/docs/source/api/varst.application.rst
similarity index 100%
rename from docs/source/varst.application.rst
rename to docs/source/api/varst.application.rst
diff --git a/docs/source/varst.cli.rst b/docs/source/api/varst.cli.rst
similarity index 100%
rename from docs/source/varst.cli.rst
rename to docs/source/api/varst.cli.rst
diff --git a/docs/source/api/varst.rst b/docs/source/api/varst.rst
new file mode 100644
index 0000000..3db1192
--- /dev/null
+++ b/docs/source/api/varst.rst
@@ -0,0 +1,9 @@
+API docs
+========
+
+.. toctree::
+   :maxdepth: 4
+
+   varst.cli
+   varst.application
+   varst.utils
diff --git a/docs/source/varst.utils.parser.rst b/docs/source/api/varst.utils.parser.rst
similarity index 100%
rename from docs/source/varst.utils.parser.rst
rename to docs/source/api/varst.utils.parser.rst
diff --git a/docs/source/varst.utils.rst b/docs/source/api/varst.utils.rst
similarity index 100%
rename from docs/source/varst.utils.rst
rename to docs/source/api/varst.utils.rst
diff --git a/docs/source/varst.utils.rst_file.rst b/docs/source/api/varst.utils.rst_file.rst
similarity index 100%
rename from docs/source/varst.utils.rst_file.rst
rename to docs/source/api/varst.utils.rst_file.rst
diff --git a/docs/source/varst.utils.substitution.rst b/docs/source/api/varst.utils.substitution.rst
similarity index 100%
rename from docs/source/varst.utils.substitution.rst
rename to docs/source/api/varst.utils.substitution.rst
diff --git a/docs/source/index.rst b/docs/source/index.rst
index 8a63a8d..77f22dc 100644
--- a/docs/source/index.rst
+++ b/docs/source/index.rst
@@ -2,13 +2,30 @@
 var ➡️ reStructuredText
 =======================
 
-Contents
-========
+Replace substitutions in rst files with variables.
+
+Installation
+============
+
+.. code:: bash
+
+   $ pip install varst
+
+Usage
+=====
+
+.. code:: bash
+
+   $ varst [-i INPUT] [-o OUTPUT] [name=value ...]
+
+
+API documentation
+=================
 
 .. toctree::
    :maxdepth: 2
 
-   varst
+   api/varst
 
 Changelog
 =========
diff --git a/docs/source/varst.rst b/docs/source/varst.rst
deleted file mode 100644
index 0c8fac0..0000000
--- a/docs/source/varst.rst
+++ /dev/null
@@ -1,27 +0,0 @@
-varst package
-=============
-
-Subpackages
------------
-
-.. toctree::
-   :maxdepth: 4
-
-   varst.utils
-
-Submodules
-----------
-
-.. toctree::
-   :maxdepth: 4
-
-   varst.application
-   varst.cli
-
-Module contents
----------------
-
-.. automodule:: varst
-   :members:
-   :undoc-members:
-   :show-inheritance:
diff --git a/varst/application.py b/varst/application.py
index 307a7d4..6222b62 100644
--- a/varst/application.py
+++ b/varst/application.py
@@ -3,6 +3,8 @@
 from typing import Sequence
 
 from varst.utils.parser import Parser
+from varst.utils.rst_file import RstFile
+from varst.utils.substitution import Substitution
 
 
 class Application:
@@ -12,10 +14,16 @@ def __init__(self) -> None:
         self.parser = Parser()
 
     def run(self, argv: Optional[Sequence[str]]):
-        """Run application
+        """Run application to replace substitutions.
 
             Args:
                 argv: Arguments vector
 
         """
         self.parser.parse(argv)
+
+        rst_file = RstFile(src=self.parser.input_file)
+        substitution = Substitution(rst_file)
+        for k, v in self.parser.variables.items():
+            substitution.update(k, v)
+        rst_file.save(dest=self.parser.output_file)
diff --git a/varst/utils/parser.py b/varst/utils/parser.py
index 10ddbf2..6c7585d 100644
--- a/varst/utils/parser.py
+++ b/varst/utils/parser.py
@@ -21,8 +21,8 @@ class Parser:
 
     def __init__(self) -> None:
         self._parser.add_argument(
-            "variables", nargs="*",
-            help="key-value pairs of substitutions",
+            "name=value", nargs="*",
+            help="name-value pairs of substitutions",
             type=_pattern_type,
         )
         self._parser.add_argument(
@@ -53,7 +53,7 @@ def parse(self, argv: Optional[Sequence[str]]) -> None:
 
         self.input_file = arg_dict['input']
         self.output_file = arg_dict['output']
-        self.variables = _parse_kv(arg_dict['variables'])
+        self.variables = _parse_kv(arg_dict['name=value'])
 
 
 _VARIABLE_PATTERN = re.compile(r"[^=]+=[^=]+")