Click on register at the top menu, fill up the details and hit register. Once successful register you will receive your password at your email and you are done with registration. Just loing useing that password. 
Click on Sell link on top menu > select the category your product/listing belongs to > fill up the details > click on Post add/product button. 
If you have not register yet, please register and loing first before you want to setup your web site. After loing click on the link Setup Website > select the shop/website category >  fill up the shop/website destials > click on post business. 

Once submited follow the system message and prompts to setup the website/shop/business. Once done select your shop/business/website under "My Account" and click on manage button on the right. It will take to to the shop/website contorl panel, where you can setup new/update pages, page section, adones sections, new articale, products, image galary, web site templates and much more.