I have no clue how to modify files in magento. I found some php files to create order in magento programatically but i have no clue where to place these files to make them run. I am pitty confuse by the architecture of magento. Please help me with that?
You can start understanding magento from official doc @ http://devdocs.magento.com/
Also there are certain blogs and tutorial on google which will help you through.