Magento techniques of uploads files inside Magento:
http://goo.gl/P11rXw
Magento form : change field from date format to datetime format
http://goo.gl/pqCuQp
Magento Update purchased downloadable product link for specific product programmatically
http://goo.gl/xqq3Td
Magento product custom option programmatically
http://goo.gl/G90qTo
