Adding new features to nopCommerce

Hi All

I am newbie in nopCommerce.
My requirement is to add new features to Administartion section and also modifying nopCommerce web like Shoppingcart section.
I want to keep the newly developed part seperate from core nopCommerce app and  upgrade process should be easy and simple.

Anyone please advice me on the best way to do it.

Thanks in advance,
Anju

Which version are you talking about?

nopCommerce 2.20

https://www.nopcommerce.com/boards/t/11315/how-to-extending-nopcommerce-v20.aspx

Have you read above link? I guess v2.2 is similar to v2.0.