You should be a little worried because it's a pretty nasty attack and it can affect you. The attack is called WannaCry (or WannaCrypt) and it's what's known as ransomware - which means if it gets into your computer it'll lock the whole thing down and make you pay a ransom to get it open again. If you don't pay after three days, the ransom can double. If you don't pay at all, you could lose all your personal files. Then once you've paid the ransom, there's no reason why the hackers can't refuse to re-open your files. It's a bad spot to be in.
You shouldn't be worried though because it's super easy to defend yourself against! If you're using a Mac, iPod or Android, you're safe - this thing only affects PCs. For PC users, don't open any suspicious-looking emails and make sure all your software is up to date - Microsoft has already patched up the hole that lets the Malware in, but you'll need to be fully up-to-date to get it. The easiest way to do this is to turn on Auto-Update if you haven't already. Type 'Updates' into your computer's search bar and it's all pretty self explanitory from there.
If however you're using an old version of Windows - we're talking Windows 8, XP or Server 2003, Windows unfortunately stopped making updates for you a long time ago, so that approach won't work. However, given the scariness of the attack, the boffins at Windows have just made a 'patch' to protect you too. Basically, if you're wearing this patch, you should be safe. You can download them from Windows here.
I suppose what we can take from this whole WannaCry incident is that while there are jerks out there trying to break into your files, there are a lot more heroic nerds online coming up with ways stop them, and most of the time (such as this instance) the good guys are two steps ahead of the bad guys. All we have to do is stay updated and not panic. Then 9 times out of 10, things will be totally fine.