Where to start, and how to learn server management

Server Config
1

Hi,
I’m a freelance webdesigner, and now I decided to learn more of server management.
I need to learn on how to maintain and increase security, run commands on server and all the basic features.
What would you recommend?
Thank you.

2

Would you like to learn Windows or Linux server management ?

3

Do you have a VPS or dedicated server yet?