I'm Kind of new with coding, so how would I set this up?
As MrPresident says previously, you'll have to create your own.
I'd recommend finding the DarkRP function where ever it stores its sourcecode (there's a git site I think), find the talktoRange function, and basically copy, modify, and rename it in your own addon file to your own.
You should be able to see how it works once you look at it for range and text distance, then find a way to replace it's chattext or whatever it uses to print to players screens with the same basic idea using a colorized version, including but not limited to using the tsayColor of ULib.
EDIT - line 48 of sv_util.lua
https://github.com/FPtje/DarkRP/blob/master/gamemode/modules/base/sv_util.lua#L48From the code, looks like you could EASILY replace the r,g,b of text 255,255,255 with whatever yellow rgb combo you wanted.
Create a function talktoRange_Yellow and go from there. (or any other function name you wanted, advert_yellow, etc).
I'd strongly recommend using whatever modules/custom addons system DarkRP recommends though, not modifying original code.
I'm not familiar with what DarkRP recommends, but, as in custom stuff for ULX, we recommend /addons/my_addon/lua/ulx/modules/...your_files_for_custom_ulxstuff