Update README.md (#24) (#15)

Author: rachellim

README.md

@@ -6,14 +6,9 @@ pre-defined set of classes for API resources that initialize
 themselves dynamically from API responses which makes it compatible
 with a wide range of versions of the OpenAI API.
 
-This library additionally provides an `openai` command-line utility
-which makes it easy to interact with the API from your terminal. Run
-`openai api -h` for usage.
-
 ## Documentation
 
-See the [OpenAI API docs](https://beta.openai.com/docs/api-reference?lang=python). (During
-the beta, you'll need to be signed into your account to see them.)
+See the [OpenAI API docs](https://beta.openai.com/docs/api-reference?lang=python).
 
 ## Installation
 
@@ -30,9 +25,50 @@ Install from source with:
 python setup.py install
 ```
 
+## Usage
+
+The library needs to be configured with your account's secret key which is available on the [website](https://beta.openai.com/account/api-keys). Either set it as the `OPENAI_API_KEY` environment variable before using the library:
+
+```bash
+export OPENAI_API_KEY='sk-...'
+```
+
+Or set `openai.api_key` to its value:
+
+```python
+import openai
+openai.api_key = "sk-..."
+
+# list engines
+engines = openai.Engine.list()
+
+# print the first engine's id
+print(engines.data[0].id)
+
+# create a completion
+completion = openai.Completion.create(engine="ada", prompt="Hello world")
+
+# print the completion
+print(completion.choices[0].text)
+```
+
+### Command-line interface
+
+This library additionally provides an `openai` command-line utility
+which makes it easy to interact with the API from your terminal. Run
+`openai api -h` for usage.
+
+```
+# list engines
+openai api engines.list
+
+# create a completion
+openai api completions.create -e ada -p "Hello world"
+```
+
 ## Requirements
 
--   Python 2.7+ or Python 3.4+ (PyPy supported)
+-   Python 3.4+
 
 In general we want to support the versions of Python that our
 customers are using, so if you run into issues with any version