I'm accesing to localhost of server to DNN installation and work fine. But I was trying to create new portal with alias : www.myalias.com and doesn't appear anything. What I did wrong? Neither works if I add new alias for default localhost portal. I have a weeks trying to serve this problem and didn't find anything helpful. Thanks.

Do I understand this correctly:

• You've installed DotNetNuke on a local computer?
• Browsing to http://localhost displays the DotNetNuke portal?
• You've created a second portal www.myalias.com and you can't see it?

I've installed DNN to server computer.
Browsing localhost/dotnetnuke works fine from server
I've created www.zagirova.com alias for new portal and can't see it, neither can see if I add same alias for default portal localhost/..

You can't see those because DNS doesn't point to them.  You would have to set up a local DNS and point it to the localhost domains for it to work. 

For local host work, it's probably easier to setup the secondary portals as child portals to the main one.  Then, the addresses that will work for local host are:

localhost/dotnetnuke               - the main parent portal
localhost/dotnetnuke/child1     - the first child portal
localhost/dotnetnuke/child2     - the second child portal

When you move these portals to a site with proper DNS, you'll adjust portalalias to match with the DNS setup.
 
You may find these tutorials helpful:

• How to backup a live hosted DotNetNuke website and restore it to a localhost installation
• How to transfer a localhost DotNetNuke installation to a live website

Attaching database gives me error:
TITLE: Microsoft SQL Server Management Studio Express
------------------------------

Failed to retrieve data for this request. (Microsoft.SqlServer.Express.SmoEnum)

For help, click: http://go.microsoft.com/fwlink?Prod...nkId=20476

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ADDITIONAL INFORMATION:

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.Express.ConnectionInfo)

------------------------------

CREATE FILE encountered operating system error 32(The process cannot access the file because it is being used by another process.) while attempting to open or create the physical file 'C:\DotNetNuke\App_Data\Database.mdf'. (Microsoft SQL Server, Error: 5123)

For help, click: http://go.microsoft.com/fwlink?Prod...nkId=20476

------------------------------
BUTTONS:

OK
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Are you trying to use the same database for multiple installations? If so, that won't work.

If not, I'd suggest that you double check the connection string to make sure that you're really connecting to the correct database.

If you have a localhost installation of DotNetNuke open and running in a web browser and you wish to attach that installations database to SQL server it will throw an error because it is being used by another process.

To attach that database, you will need to close your browser window and wait for DotNetNuke to release the database, once it has released control of the database you will be able to attach it without errors. - (it can be quicker to just restart your computer + go straight to SQL server to attach the database rather than wait for DotNetNuke to release the database.)

Hope this helps,