Heya! In order to use nicknames with colors you must be able to use ./nick by having a donator rank such as VIP, VIP+, etc. If you already have a rank, use the command ./nick and use these color codes listed in the screenshot: https://prnt.sc/uzifdx :D
If you have VIP or higher but are struggling with the colour codes, you can always ask someone to make a nick for you. Just give them what colours you want and they can make you a nick that you can just copy-paste. Hope this helps ^^
If you're VIP, you can use &~ in your name! If you're MVP, you can use &~ in the chat!
Here's what &~ is what:
&0 - black
&1 - dark blue
&2 - dark green
&3 - blue
&4 - dark red
&5 - purple
&6 - orange
&7 - light gray
&8 - dark gray
&9 - violet
&a - lime
&b - light blue
&c - red
&d - pink
&e - yellow
&f - white
&l = bold
&o = italic
&k = gibberish nonsense
&n = underline
&m = strikethrough
&r = reset back to white normal text
On top of what everyone else said, Labymod also has the emoji module that has all the color/effect codes that make it easy to do more complicated color combinations.