"Can anyone suggest how can I secure my computer when I surf the Internet"
"Most basic is a proxy https://en.wikipedia...ki/Proxy_server
Could you please explain your logic here where a proxy or vpn or tor secures your computer? Secures it from what? Now with the use of the proxy, if it was doing filtering - then sure it could secure your computer from bad sites. Code can be verified by the proxy, ie any viruses, bad sciprts, etc. So DEPENDING on what proxy your using this could be the case where your computer is more secure than not using one. But then again if your using some fly by night proxy to hide, it could be even the opposite. They could inject crap! They could be tracking everything your doing, they could be redirecting you through other sites for your searches, etc. etc.. So that sort of blanket statement can be very misleading to a user - just because your using some proxy does not by default make your computer more secure. What proxy are you using has to be asked - are you using a company run proxy as the only way out of a network? Or some random one you found by searching on the internet so you could bypass some restriction based on ip, etc.
As to VPN - this normally does nothing then route your traffic differently. Can it hide your traffic from the local network/isp - sure. But not sure I would consider that securing his computer. He would still be open to bad code on sites for example. And depending on the vpn service in use - you could be opening up yourself up to privacy concerns - since you might be hiding your traffic from your local/isp network, but your also now routing ALL traffic through some VPN provider - do you trust them?
Tor is would be the same a vpn in this case - only your routing your traffic through many different connections, but there is nothing securing your computer from what you hit when you come out the other end of the tor network.
The OP post is so vague that it makes it almost impossible to answer with any sort of actual useful advice. Secure his computer from WHAT is the piece of information that is missing.