Entusiasta da Corrida de Bronze

You will find it in your achievements if you search. Here it is on Wowhead:
Link

You have to get SIlver in all the Dragonriding races in the four original zones, in both the regular and Advanced (but not Reverse).

So you have to get Waking Shores: Silver
https://www.wowhead.com/achievement=15916/waking-shores-silver#
and
Waking Shores Advanced: Silver
Link#

and the same for the three other zones. And you have to do each of these races within an achievemet on the same character. Probbaly simplest and safest to do everything on one character.

There are guides on Wowhead and videos on YouTube. I found only two or three (one in Thaldraszus especially) gave me any problem at Silver level. Gold can be a lot harder for some, but you don't need Gold for the pet!

Thank you! I'll check it out right now. So I need to look for each zone and then silver and advanced silver. I wish Blizz had made that a little easier to find, but I really appreciate your help.

Yes. In each of the zones there are about 8 races. You don't have to wait for a world quest; the NPC is available to start you whether the WQ is up oe not. Do each race on Silver and on Silver Advanced.