Python
Python is very easy to learn and use, one of the easiest of all programming languages. Even if you have not programmed in Python before, you shouldn't have much trouble picking it up quickly. I'll let you absorb it mostly through examples. There are two traps, however - one mildly unusual, the other severely annoying:

indentation in programs is an important part of their structure;
division of integers is true integer division: 5/4 = 1, -3/2 = -2, 1/2 = 0. It is this last that will cause much trouble. Usually, write 1/2.0 or 1/float(2).

There are a few other quirky features of the language. You might want to skim quickly one of the appendices to the manual for PiScript:

Appendix 2 - A brief introduction to Python
And if you need Python help, Google is probably your best bet. For example, if you want to know about atan in Python, Google python atan.