r - Advice for learning how to use httr to access API -

I try to know how to use the httr to access the SMS service API I am doing Package documentation is useful, but I think there is a lack of understanding of some important high level concepts. Can anyone tell me a good tutorial for using the httr ?

If I can help guide you on the right type of resource, then it is an example of a URL that I am trying to use from the service provider's API documentation (the account is not active) :

  http://sms.shujaa.mobi/sendsms?username=info%40shujaa.co.ke&password=info&account=developer&source=2024&destination=254717555555&message=This % 20is  
  Library (Optimizer Url & lt; - "http://sms.shujaa.mobi/sendsms" Username & lt; - "Information% 40shujaa.co.ke" Password & Lt; - "information and account" account  
 I will begin to catch up with OAuth, and the keys to full access to all API features, Use secret, token, etc. ...  
  httr  However the correct package to use is ...  
 Please enter your other API connection Take a look at the answer  
  
 Hope that helps ... If you tell us what the service is, it is because we can help you ...