Can someone help me in integrating sendgrid into my own org? I need to send bulk email(for campaigns) to a specified list of recepients. 

I took some help from here. https://github.com/sendgrid/sendgrid-apex

But when I tried implementing it in my or, I always had a compiling error
Error Error: Compile Error: Illegal assignment from SendGrid.SendGridResponse to String

Please suggest. Thanks for your time.