link two tables together MYSQL

I know this is extremely simple, I just need two tables to link within my mysql database. I have joomla virtumart vt1_vm_orders (table) and vt1_chronoforms_squarefril (table) correct me if i am wrong but i just want for instance if you think this will work cf_id within vt1_chronoforms_squarefril (table) that is auto inc and order_id within vt1_vm_orders (table) that is auto inc so my site will display information if they are the same id, I know the below is wrong hence why i am posting here. my wrong code: $db_temp = new ps_DB; $q = "SELECT date_9, cf_id, order_id"; $q = "FROM vt1_chronoforms_squarefrill, vt1_vm_orders"; $q = "WHERE vt1_chronoforms_squarefrill.cf_id = vt1_vm_orders.order_id)"; $db_temp->query($q); $db_temp->next_record(); $myInfo = $db_temp->f("date_9"); $body = str_replace( "[DATE_9]", $myInfo, $body);