Script created in namespace has limited access to everything

Hey guys, I am using the UnitySteer package, and it has a set of steering behaviours contained in a folder/namespace. I want to add one of my own steering behaviours in this folder. Problem is, that any script created in this has limited access to everything. Heck, even MonoBehaviour 'does not exist in this context'! Due to this I am not able to derive from another class in the namespace which I so much need! The only way now is to edit one of the existing behaviours/scripts! What am I doing wrong? Is there anything I have to do to gain access to namespaces?I just used the same format as all the other scripts were having. Here is the link to the package (https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjmtpD_x-vMAhVFOI8KHVgkDMgQFggcMAA&url=https%3A%2F%2Fgithub.com%2Fricardojmendez%2FUnitySteer&usg=AFQjCNH52VI_VPHwuemKoIJBWuWvlM-gpw&sig2=pG1rIahefmhaI2D-xmwOzw)