Database restore process

Hi guys…
its been amazing experience that i have learn this open source program…

how can i use restored database on my server…
i tried to restore it using the bench restore
then ask me the mysql password
then gives error document already exist. If my document is existed on mysql.

how can i test and used my restored database in my erpnext browser??
i tried bench --site migrate but nothing happends…
Please help me…

Thank you…