Installing pythonstartup file

How do I install the pythonstartup file so that it runs on command like python myfile.py?

I tried to install it into my /home/myuser directory for Ubuntu, but it said that I had insufficient permissions. Furthermore, different places say alternately that it should be in all caps or in all lower case with a period before it. The Python command line guide does not seem to explain where to put the file, or how to change which environment variable to 'point' to it.