📝 add getting started in README.

README.md

@@ -5,15 +5,45 @@
 ![GitHub License](https://img.shields.io/github/license/cemc-oper/cedarkit-comp)
 ![GitHub Action Workflow Status](https://github.com/cemc-oper/cedarkit-comp/actions/workflows/ci.yaml/badge.svg)
 
-气象数据计算库
+A calculation tool for meteorological data.
 
-## 安装
+## Install
+
+Install using pip:
 
 ```bash
 pip install cedarkit-comp
 ```
 
-## 使用
+Or download the latest source code from GitHub and install manually.
+
+## Getting started
+
+Load data from file:
+
+```py
+from reki.format.grib.eccode import load_field_from_file
+
+file_path = "/some/path/to/grib2/file"
+field_h_500 = load_field_from_file(
+    file_path,
+    parameter="gh",
+    level_type="pl",
+    level=500
+) / 10.
+```
+
+Smooth using `smth9`:
+
+```py
+from cedarkit.comp.smooth import smth9
+from cedarkit.comp.util import apply_to_xarray_values
+
+field_h_500 = apply_to_xarray_values(
+    field_h_500, 
+    lambda x: smth9(x, 0.5, 0.25, False)
+)
+```
 
 ## LICENSE