Add usage to readme

Author: kimpepper

Diff for: README.md

@@ -1,9 +1,65 @@
 # Nested Set
 
-A PHP library for a Nested Set implementation.
+A PHP Doctrine DBAL implementation for Nested Sets.
 
 [![CircleCI](https://circleci.com/gh/previousnext/nested-set.svg?style=svg)](https://circleci.com/gh/previousnext/nested-set)
 
+## Using
+
+### Create table schema
+
+Create the table schema, passing in a a [DBAL connection](http://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/configuration.html#getting-a-connection) and table name (defaults to 'tree').
+```php
+$schema = new DbalNestedSetSchema($connection, 'my_tree');
+schema->create();
+```
+
+### Set up the nested set client
+
+Create a new `DbalNestedSet` passing in the DBAL connection and the table name.
+
+```php
+$nestedSet = new DbalNestedSet($connection, 'my_tree');
+```
+
+### Add a root node
+
+A NodeKey represents a unique ID for a node in the tree. It supports the idea of a node ID and a revision ID, mostly for compatibility with Drupal.
+
+```php
+$nodeKey = new NodeKey($id, $revisionId);
+$rootNode = $nestedSet->addRootNode($nodeKey);
+```
+
+### Add a child node
+
+To add a child node, you provide the parent node, and a child node key.
+
+```php
+$nodeKey = new NodeKey($id, $revisionId);
+$nestedSet->addNodeBelow($rootNode, $nodeKey);
+```
+
+### Find Descendants
+
+To find descendents, you provide the parent node key.
+
+```php
+$nodeKey = new NodeKey($id, $revisionId);
+$descendants = $this->nestedSet->findDescendants($nodeKey);
+```
+
+### Find ancestors
+
+To find ancestors, you provide the child node key.
+
+```php
+$nodeKey = new NodeKey($id, $revisionId);
+$ancestors = $this->nestedSet->findAncestors($nodeKey);
+```
+
+See `\PNX\NestedSet\NestedSetInterface` for many more methods that can be used for interacting with the nested set.
+
 ## Developing
 
 ### Dependencies