>>When you get Login dialog just open Server name combo. There you should have all instances of your server + all servers SSMS found.
>
>It gives me 2 servers. One I can connect using Windows Authentication, another I can not.
>
>>Also if you open SQL Server Configuration Manager there you could see what services you have. On my office computer i have:
>>SQL Server (MSSQLSERVER)
>>SQL Server (SQLSERVEREXPRESS) (or something like that)
>>
>>Right click on every instance and see all properties for it.
>
>If I found my database files in one directory, how can I make them available in the instance I'm running this?
>
>Thanks again.

Try to attach it there with SSMS.
Right click on databases node->Attach...

But if that database is attached to other instance you should detach it first.