i want to different between on page and off page activities....
Very simple words. On page mean your site internal optimization. Exmp- meta keyword, Page heading etc. Off page mean external site link building. Exmp- Link Building with anchor text, traffic sites ads, adword advertising etc.
Please use the forum search function before asking such basic questions. You will find lots of threads with answers to that same question. Then, if you have any specific questions, don't hesitate to ask them.