The only quick answer is to spend some time reading around this wonderful site and doing a bit of research. After that its easy...
Its really a subtle and varied thing - you could help by giving more detail such as domain name, keywords, niche, etc - some are easy - I could probably get a site about Invisible Levitation Jelly in to the top 10 in a week. But a site about Web Hosting would take a bit longer. Its not a quick fix and a quick answer situation.
Ahh, the 'holy grail' of SEO.... No simple and straightforward answer to that one. Read everything you can find about search engine optimization starting right here on the DP forum. Then you will start to realise why there is no simple answer. T