How do i win this keyword .... ??

Hi all!
I'm sorry for my bad english skill, i hope all of you can understand what i say!
I have read allmost forum post in Blackhatword and i want to promote this keyword "kim tu dien" for my local google in Viet Nam. I had worked hard in 4weeks (buil backlink, write acticle, bookmark.... ) but still now i am in 18 position for this keyword, very sad.
Please give me some advice.

18th position in Google in a period of 4 weeks is not bad if the keyword is competitive. You need to continue the pace of link building to see your position getting better.