How to get a domain name
To start online you need a domain name (esmailelbob.xyz for example) and there are many and many websites that give you ability to buy domain names. There is famous ones like godaddy and namecheap and there are others called offshore domain resellers (more on that later)
Which company you will buy domain from it depends on your goal. But most people say godaddy is bad so avoid this by all means also lately the epik hack showed how they were bad about security so avoid them too! You can give try for namecheap
But look out, Most domain registrars force you to type personal data such as address or real full name and websites like whois lookup can actually show these info easily, you can lie about data you enter but if company knew they will close your account and domain name. Here comes into play something called offshore domain registrar. They buy domain for you but under their name so if someone used whois lookup they will find data of company you bought from. In my case I use Njal.la and so far my experience is okay with them. Maybe only downside that their prices are little high (for me around 200EGP per year) but you know what, it's a little price to pay for privacy
If you want to hide your real info online you might give try for offshore domain registrars and if it's okay for you to show your data (or buy more for whois guard from company you buy the domain from) then you might give a try for namecheap or something similar!