user table at wordpress

I have a site and I want to add a worpress blog.I set

define('CUSTOM_USER_TABLE', 'en_net_usrs_tb');

define('CUSTOM_USER_META_TABLE', 'wp_usermeta');

to locate the user table of my site at worpress. But en_net_usrs_tb has not the same username and user password as the wordpress so worpress look at wrong fields.How can I fix it? I hope to be understood.

Also is there a way to set user as "log-in" to the worpress site when he is log in at the main site.