i´ve purchased Proyect Zomboid with some friends but we cant access to the servers we created. It says conection error. What are we suppose to do to be able to play in our own server? We've searched everything in host server options but still we cant find a solution.

Did you solve the problem already? If not, here is a comprehensive guide to setup a dedicated server:

https://pzwiki.net/wiki/Dedicated_Server

Are you all on the same LAN or do some of you connect through an internet router? If the latter, you'll have to forward the UDP ports 8766 and 16261 from the router to the machine running the server.

Otherwise, we'll need more information about your setup. How do you run the server(s) exactly? On which OS? How do the players try to connect?