How do I do this query in tables with msql

Hi, I have this code to make queries to some related tables, what I want to do is weigh the parameters but I can not find the way, the parameters that I want to pass are those of the municipality, for when searching for example, municipality lander, only show me the data I ask but the municipality lander thank you for your help in advance.

this is the code

       <?php


       include('conectar.php');


       $result=mysqli_query($con,"SELECT a.nombre, b.idnombre, b.municipio 
       FROM 
       datos a, centrosv b where a.id_votacion=b.idnombre " );

       while ($registro = mysqli_fetch_array($result))


       {

       echo"
       <span id='hitoria'>
       ".$registro['nombre']."'<br>
       ".$registro['idnombre']."'<br>
       ".$registro['municipio']."
       <br><br>
       </span>

       ";

       }

       ?>