First thing to do is access your admin page, from here you should be able to see an Apps drop down menu, from within it click Manage Apps.
On the bottom of this page you can ‘Click here’ for developers wanting to develop new applications which will take you to another page. On this page you will be given you the option to ‘Generate new application’ and when you click on this it will reveal your API Key and Password
Also remember your account name is not your full URL, it is the bit before .myshopify.com. E.g. if your Shopify page is http://bluehandbags.myshopify.com, your account name is simply bluehandbags.