Clarify mock request order of operations in README

It wasn't apparent, at least to me, from the README that you specified the test responses AFTER your code started an Ajax request.

README.markdown

@@ -16,6 +16,7 @@ Using the library in your Jasmine specs consists of four parts:
 
 1. Defining test responses
 2. Installing the mock
+3. Triggering the ajax request code
 3. Defining the response for each request
 4. Inspecting Ajax requests and setting expectations on them
 
@@ -99,7 +100,19 @@ Install the mock using `jasmine.Ajax.useMock()`:
       ...
 After this, all Ajax requests will be captured by jasmine-ajax. If you want to do things like load fixtures, do it before you install the mock (see below).
 
-### 3. Set responses ###
+### 3. Trigger ajax request code ###
+Before you can specify that a request uses your test response, you must have a handle to the request itself.  This means that the request is made first by the code under test and then you will set your test response (see next step).
+
+        foursquare.search('40.019461,-105.273296', {
+          onSuccess: onSuccess,
+          onFailure: onFailure
+        });
+
+        request = mostRecentAjaxRequest();
+
+The onreadystatechange event isn't fired to complete the ajax request until you set the response in the next step.
+
+### 4. Set responses ###
 Now that you've defined some test responses and installed the mock, you need to tell jasmine-ajax which response to use for a given spec. If you want to use your success response for a set of related success specs, you might use:
 
     describe("on success", function() {