Why can't I do Imaginary numbers?

Here are some you tube clips and other resources.  Perhaps one of these will help.  

https://www.google.com.au/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=introduction%20to%20complex%20numbers

Imaginary numbers is a very broad topic so perhaps you cold be more specific and we could help you.  :)