If you have chosen Keil C51, you should obtain a copy of their free CD and visit their website. Both contain a wealth of examples.

The CD includes the full documentation for the C51 toolchain - you should read the "Getting Started" guide (gs51.pdf) and work through the example projects.

Note that Keil also have a discussion forum for topics specific to their tools:
www.keil.com/discuss
but please, do read the documentation first!!