One of my friend is using premium account with Blue Host, last december I purchased a addon domain through his account and running wordpress blog.
Please provide me some info about VPS ..How to set up. Bcoz "I dont want to take risk, If traffic increase my site will crash"
What are you looking for? Do you want to transfer your addon domain from your friends account to a new VPS? This should not be to tough of a task. Try getting a VPS that's managed, and they should be able to help you out, alternatively, you can look for an outsourced server manager to set things up for you and keep them running.