People usually have problems on the Internet because they have no idea about how to surf on the web.
Internet is a place where you can find people like hackers or trolls, and they can do things to you like stealing files or bank account information that you could have on your personal Cloud or get into your privacy. For this reason is very important to know all the websites that you visit, and to whom are you talking to in the social networks.
When you want to download something like a movie or archives, you could get some virus or malware that can hurt your computer.
My advice for this is find the origin of the archive and have an antivirus, you can get one free, but it would be limited and it does not have all the security options that you could have if you pay a monthly fee.
If you do not want, that person who you do not know to see your pictures, do not accept them and do not publish pictures with ambiguous content, maybe they can blackmail you whit information that they have about you.
However, if your account is public, do not publish personal information or do not upload to the cloud personal information, people can use it for get in to your house when you are not in and they can get your password account. You should have different passwords four you e-mail and social networks, and it could be good changing passwords from time in time. A safe password should have numbers, symbols, capital letters, and lower case letters and should not be easy to guess.
In conclusion, you must to be careful when you are on the Internet, knowing to whom you are talking because if they are trolls or hackers, they could blackmail you or do something worst, and get an antivirus in all of your devices to get them save of malwares.