update readme

Author: honzap

README.md

@@ -1,2 +1,74 @@
 # python-ing-api
+
 Python interface for ING IB
+
+Provided class enables very simple interface to read data from API 
+provided by ING Bank. This service is currently deployed in 
+[Czechia](https://ib.ing.cz/transactional-cz/) where the library 
+has been tested.
+
+## Usage
+
+For the usage the `requirements.txt` must be installed to the 
+environment.
+```bash
+pip3 install -r requirements.txt
+```
+
+### Before Using
+Before using the library you should log in into the Internet Banking.
+- [Czechia](https://ib.ing.cz/transactional-cz/)
+
+When the login process is done and you're successfully logged in open 
+the developer console of the browser. You should there network requests 
+and take of of the requests going to bank API. It should contain the 
+`/rest` part in the path. Then, find `Request headers` and there 
+the `Cookie` header. Copy the whole value of the header and use it to
+ set up the `IngClient`. 
+ 
+> Keep in mind that you should stay logged in when you would like to
+ run the script. 
+
+### Initialize code
+```python
+from ing_api import IngClient
+
+# set up cookie
+cookie = 'copied value of Cookie header from browser'
+api = IngClient(cookie)
+```
+
+### Get information about the client
+```python
+client = api.client()
+```
+
+### Get all products of the client
+```python
+products = api.products()
+```
+
+### Get list of transactions (movements)
+In the terminology of the API the transactions are called movements.  
+
+```python
+product_id = 'uuid'
+from_date = datetime.date(1970, 1, 1)
+movements = api.movements(product_id, from_date=from_date)
+print(movements['count'])
+```
+
+Arguments are:
+- `product_uuid` - UUID of selected product
+- `from_date` - starting date (required)
+- `to_date` - ending date of selection (default is today)
+- `limit` - number of items which should be loaded once - pagination (default: 25)
+- `offset` - offset for pagination (default: 0)
+
+### Get transaction (movement) detail
+The information provided in the list of movements is not complete. For 
+the detailed information the detail should be called.
+
+```python
+movement = api.movement('uuid')
+```