如何使用嵌入式C启动ARM皮质编程?

I am familiar with 8051 C programming .Now I want to learn ARM cortex M3 programming . I have STM32F103C8T6 development board with ARM Cortex M3 Processor, it's programmer and Keil compiler.I want to do small projects with it for example blinking LEDs ,SPI and I2C programming etc. I am having little knowledge about arm architecture . Many people on blogs say directly start programming instead of reading architecture or reading hundred pages ARM datasheet. I don't understand how is it possible. I am familiar with 8051 C programming .Now I wa