I wanna make the DB so only the user logged on can see only theri own profile ....and theri is no search....can I do this?

Yes you can this. From the dbman Readme.txt file:

3. Modify/View Own. If you use modify/view own, you must define a "Userid" field in your database and set $auth_user_field to it's position. See the default config file as an example.

i dont get it.THis is new to me.Can you tell me EXACTLY what to do

1) You need to have a field named Userid in your default.cfg file.

2) set $auth_user_field (in default.cfg) to the position number for the Userid field.

Example:
Validated => [7, 'alpha', 0, 3, 1, 'Yes', 'Yes|No'],
Popular => [8, 'alpha', 0, 3, 0, '', ''],
Userid => [9, 'alpha',-2,15, 0, '', '']

The 9 above is the position number for the Userid field.

The entry in authorizations then becomes:
$auth_user_field = 9;

isnt that default though?

Yes, this is default unless you've made changes to the fields. You would also need to identify what permissions you want users to have using the permissions settings which is also in the default.cfg file.

Alex has provided several examples on permission settings in the Readme.txt file included with the dbman files.

When making changes in the permission settings,
(1 = "yes", 0 = "no") << Taken from default.cfg file.