WannaCry infects only machines running Windows operating systems. If you do not update Windows, and do not take care when opening and reading emails, then you could be at risk.
However, home users are generally believed to be at low risk to this particular strain.
You can protect yourself by running updates, using firewalls and anti-virus software and by being wary when reading emailed messages.
Regularly back up your data so you can restore files without having to pay up should you be infected, as there is no guarantee that paying the ransom will result in your files being unlocked.
The UK’s National Cyber Security Centre website contains advice on how to apply the patch to stop the ransomware – MS17-010 – and what to do if you can’t.