How do I make code interact with hardware?

I have an idea for a project that requires some programming but I’m not quite sure where to go from there. I’ve written some lines of code in Python 2.6 that currently works by me inputing numbers and then getting a text output. My question is how do I make something such as a speedometer input the values rather than myself? Also, instead of text I would like the output to control LED’s.

This whole setup needs to be somewhat portable (not on my computer). So does anyone have an idea how I should go about doing this? Thanks in advanced and just ask if something’s unclear.