ı don't work the enterprise manager.

Enterprise Manager is a separate product that you can install to manage ALL databases/servers/??? in the "Enterprise".

Oracle comes with a limited version built in version.  In 11g it was still called DbConsole.

I would start in the docs:
https://docs.oracle.com/cd/E11882_01/server.112/e25494/dbcontrol.htm#ADMIN13401

Also have a look at Chapter 3 at the following link .

"This chapter introduces you to Oracle Enterprise Manager Database Control. The Oracle Universal Installer installs Oracle Enterprise Manager Database Control when you install the Oracle software. Enterprise Manager Database Control provides a Web-based interface that you can use to manage your Oracle instance and database"

https://www.oracle.com/webfolder/technetwork/tutorials/obe/db/11g/r2/2day_dba/gettingstarted/gettingstarted.htm

hi .
as sys login to the system.
but
web site said that 'internal error has occurred '

I cannot see database data in enterprise manager.

C:\WINDOWS\system32>emctl status dbconsole
Oracle Enterprise Manager 11g Database Control Release 11.2.0.1.0
Copyright (c) 1996, 2010 Oracle Corporation.  All rights reserved.
https://DESKTOP-OE75BI7:1158/em/console/aboutApplication
EM Daemon is not running.
------------------------------------------------------------------
Logs are generated in directory C:\app\musti\product\11.2.0\dbhome_1/DESKTOP-OE75BI7_orcl/sysman/log

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try running the following command.

emctl start dbconsole

cmd in windows in my own user session

>C:\Users\musti>emctl start dbconsole

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C: \ Users \ musti> emctl start dbconsole
Oracle Enterprise Manager 11g Database Control Release 11.2.0.1.0
Copyright (c) 1996, 2010 Oracle Corporation. All rights reserved.
https: // DESKTOP-OE75BI7: 1158 / em / console / aboutapplicatio's
Starting Oracle Enterprise Manager 11g Database Control ... The service name is invalid.

NET HELPMSG 2185 for more help.

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BUT
cmd in windows in   administrator session

C:\WINDOWS\system32>>emctl start dbconsole

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when ı wrote

Oracle Enterprise Manager 11g Database Control Release 11.2.0.1.0
Copyright (c) 1996, 2010 Oracle Corporation.  All rights reserved.
https://DESKTOP-OE75BI7:1158/em/console/aboutApplication
 - An instance of Oracle Enterprise Manager 11g Database Control is already running.

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cmd in windows in my own user session

C: \ Users \ musti> emctl status dbconsole

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when I wrote

Oracle Enterprise Manager 11g Database Control Edition 11.2.0.1.0
Copyright (c) 1996, 2010 Oracle Corporation. All Rights Reserved.
https: // DESKTOP-OE75BI7: 1158 / em / console / aboutApplication
Access Denied.
EM Daemon does not work.
-------------------------------------------------- ----------------
Logs are created in C: \ app \ musti \ product \ 11.2.0 \ dbhome_1 / DESKTOP-OE75BI7_orcl / sysman / log

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I've not worked with DbConsole or 11g for a long time so everything will be from memory.

I would first try to drop and recreate the repository.  Since you've never used it, there cannot be anything in it you want...

https://docs.oracle.com/cd/E18283_01/server.112/e17120/dbcontrol005.htm