Considering all methods to improve a certain piece of content, the way you distribute keywords in your text is probably the less important one. First of all you have to control the meta-tagging.
I didn't understand your question regarding the backlinks, sorry.
Thanks for the explaination. Regarding the backlink, how can we increase the links from other websites that refers our website. I heard there are some software to generate backlinks but i believe too much of backlinks can lead to google penalizing our website
Correct, an excessive distribution of backlinks will be penalized by Google's feature called Penguin. Even an over-optimized achor text can be considered spam in that context. That's why you need to build a smart network of several pages that support each other without abusing the algo.
i think the best idea to rank is to write a good and content which is actually useful and informative, and just submit it into google webmaster - it works slowly, but it's much more effective
I didn't know about it. Will definitely give it a try.