In order to secure your computer you will need to close certain ports, block certain ICMP request, add extra security to network traffic, etc. Doing this manually could be hard to accomplish and instead you will need to install a security solution that is already available and does all those things automatically. I have performed a search query on Software Informer's section with the term "internet security" which lists all the available solution for you to use. You can pick a freeware solution or a shareware one, based on your preference. Once you decided, download the application, install it and let it run in the background protecting your computer.