I read some articles about configuration of Ubuntu, Lots of articles written based on 12.04 not 14.04, but 14.04 is the new version now
Which Ubuntu version is better to WordPress?
Both 12.04 and 14.04 are LTS (Long Term Support) versions of Ubuntu so while 12.04's age means that there are more tutorials and information available related to it now this should shift towards the newer LTS release over time. Since 12.04 will eventually be depreciated before 14.04 since it is an older release I would recommend starting with 14.04.