Hello
I am working in Embedded system for about 4 years. The major products that i used for my designs were 8bit MCUs of microchip but now i want to extend my work and knowledge so i am decided to use Qualcomm products.
Now can anyone help me how to start and how to continue?

 

You will be out of luck with anything Broadcom or Qualcomm - they have heavy-handed non-disclosure agreements based on the size of the business opportunities and traditionally release only minimal information about their devices.

Depending on what you want to do, hobbyist-friendly companies would be found in TI, Freescale, NXP, ST, etc.

Alternatively, you might want to start from a community supported development board with a ton of support and code available: you mentioned Qualcomm, so I suspect you are looking for Cortex A applications processors. For these, you can look at the Beaglebone or Raspberry Pi.