For basic model airplane design, you can use "R/C Model Aircraft Design" by Andy Lennon... Amazon.com has it.
You should get a grounding in the basics of flight and aerodynamics in order to accomplish your end goal with the least amount of trial and error.
The delta is a special form of airplane, and needs more care in how it is designed..
A more advanced reference would be Martin Simons' "Model Aircraft Aerodynamics", also available from Amazon. There's more of the theory than Lennon has, but Lennon's book will get you there.