Hello,
There is an industrial programming standard for PLC's called IEC 61131-3. This covers the five common PLC languages: structured text, ladder diagram, function block programming, instruction list and sequential function block. The spec also defines variable type names, and basic PLC configuration, which should (in theory anyway) make it easier to switch between manufacturers platforms. http://en.wikipedia.org/wiki/IEC_61131-3
If you're new to PLC's you might want to start with an IEC based system (Like CoDeSys, Unity, etc.) rather than one of the proprietary systems.
I have some YouTube tutorials on using CoDeSys, that you might find useful. There is a demo version available as a free download, and the software has a built in simulator for testing your program without any hardware. (Disclosure: I work for WAGO a PLC manufacturer that uses CoDeSys, but several other manufacturers also use this development environment.)
Thanks SCADA_Dude but I'm under going training for Keyence, OMRON, AB PLC's want to now How to start my career and where can i get jobs.......... thanks for sending valuable links.