README.md in lipseys-0.1.0 vs README.md in lipseys-0.1.1

@@ -18,10 +18,109 @@
 
     $ gem install lipseys
 
 ## Usage
 
-TODO: Write usage instructions here
+**Note**: Nearly all methods require `:email` and `:password` keys in the options hash.
+
+```ruby
+options = {
+  email: '[e-mail]',
+  password: 'sekret-passwd'
+}
+```
+
+### Lipseys::Catalog
+
+There are several methods you can use to fetch different kinds (or all) items in the catalog.
+All of the listed methods return the same response structure.  See Lipseys::Catalog for details.
+
+```ruby
+# All items
+catalog = Lipseys::Catalog.all(options)
+
+# Firearms only
+firearms = Lipseys::Catalog.firearms(options)
+
+# NFA / Class 3 items only
+nfa = Lipseys::Catalog.nfa(options)
+
+# Optics only
+optics = Lipseys::Catalog.optics(options)
+
+# Accessories only
+accessories = Lipseys::Catalog.accessories(options)
+```
+
+### Lipseys::Inventory
+
+There are similar methods for getting your account's inventory (availability, price, etc.).
+All methods return the same response structure.  See Lipseys::Inventory for details.
+
+```ruby
+inventory = Lipseys::Inventory.all(options)
+firearms = Lipseys::Inventory.firearms(options)
+nfa = Lipseys::Inventory.nfa(options)
+optics = Lipseys::Inventory.optics(options)
+accessories = Lipseys::Inventory.accessories(options)
+```
+
+### Lipseys::Order
+
+In addition to the `:email` and `:password` keys in the options hash, submitting an order requires
+the following params:
+
+```ruby
+options = {
+  email: '[e-mail]',
+  password: 'sekret-passwd',
+
+  item_number: '...',  # Lipsey's item number
+  # - OR -
+  upc: '...',  # Universal Product Code
+
+  quantity: 1,
+  purchase_order: 'PO-123',  # Application specific Purchase Order
+
+  # Optional order params:
+  notify_by_email: true,  # If you want an email sent when the order is created
+  note: '...',  # Any notes attached to the order
+}
+
+response = Lipseys::Order.submit!(options)
+```
+
+The response will have this structure:  (See Lipseys::Order for more details)
+
+```ruby
+{
+  order_number: '...',
+  new_order: (true/false),
+  success: (true/false),
+  description: '...',
+  quantity_received: Integer,
+}
+```
+
+### Lipseys::Invoice
+
+In addition to the `:email` and `:password` keys in the options hash, finding an invoice requires
+either an `:order_number` **OR** a `:purchase_order` param.
+
+```ruby
+options = {
+  email: '[e-mail]',
+  password: 'sekret-passwd',
+
+  order_number: '...',  # Lipsey's order number
+  # - OR -
+  purchase_order: '...',  # Application specific Purchase Order submitted with the order
+}
+
+invoice = Lipseys::Invoice.all(options)
+```
+
+See Lipseys::Invoice for the response structure details.
 
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.