Created Usage (markdown)

Usage.md

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+**Note:** All the snippets below assume you have created and started a Client instance.
+You also must be authorized, that is, a valid `*.session` file does exist in your working directory.
+
+## Simple API Access
+
+The easiest way to interact with the API is via the `pyrogram.Client` class which exposes [bot-like](https://core.telegram.org/bots/api#available-methods) methods. The purpose of this Client class is to make it **even simpler** to work with Telegram's API by abstracting the raw functions listed in the API scheme.
+
+The result is a much cleaner interface that allows you to:
+
+- Get information about the authorized user:
+
+  ``` python
+  print(client.get_me())
+  ```
+
+- Send a message to yourself (Saved Messages):
+
+  ``` python
+  client.send_message(
+      chat_id="me",
+      text="Hi there! I'm using Pyrogram"
+  )
+  ```
+
+## Using Raw Functions
+
+If you want **complete**, low-level access to the Telegram API you have to use the raw `functions` and `types` exposed by the `pyrogram.api` package and call any Telegram API method you wish using the `send` method provided by the Client class:
+
+- Update first name, last name and bio:
+
+  ``` python
+  from pyrogram.api import functions
+
+  client.send(
+      functions.account.UpdateProfile(
+          first_name="Dan", last_name="Tès",
+          about="Bio written from Pyrogram"
+      )
+  )
+  ```
+
+- Share your Last Seen time only with your contacts:
+
+  ``` python
+  from pyrogram.api import functions, types
+
+  client.send(
+      functions.account.SetPrivacy(
+          key=types.InputPrivacyKeyStatusTimestamp(),
+          rules=[types.InputPrivacyValueAllowContacts()]
+      )
+  )