What do I need to do to go to Shenzhen/Guangzhou for 2 weeks?

I want to go China ShengZhen or GuangZhou for 2 Weeks, just for visiting or travel.
What do i need to do ?
How am i apply Visa ? If need to fill form, where can i get the form ?
How much the fee i should pay ?
I intend to go China through Singapore Airport.
Thank's.