How to make it so I have nicknames on my minecraft server?

You have 2 options.
1. Put your server in offline mode and change your username "display name" manually

Search on google "change minecraft name server"

2. Get a bukkit server and install essentials. Then you can use /nick.

You need to use craft bukkit on the server and then use a plug in called essentials… Then you can use /nick {namehere}