Below is a step by step installation procedure to install DotNetNuke portal version 3.x on our server.
To have DNN 3 installed, you need to have one MSSQL database.
Please backup all your existing files before you done any DNN installation.

Installation Instructions

A) Getting DotNetNuke and Uploading to Webserver

- Download DotNetNuke from http://www.DotNetNuke.com

- Upload the zip file from FTP, and then later on unzip the file using Copanel's File Manager.
- After that move all the files using File Manager from unzipped folder to the root folder (public_html) of your  website.
- Create a new Database from your copanel.
- Set the read and write permission for ASP.net,IUSR and IWAM for the root folder (public_html)
For more info on how to set read and write permission
Please refer to  http://kb.seekdotnet.com/ViewArticle/110data.aspx

B) Customizing the web.config file

- Rename the Release.config to web.config

- Open the Web.config file (under root) with any text editor.

- Update the database connection information to the database that you created in previous steps.

   <add key="SiteSqlServer" value="Server=<localhost>;Database=<DB_NAME>;uid=<User_Name>;pwd=<DB_password>;Trusted_Connection=False" />
-Update the highlighted fields with your account information
-Add "Trusted_Connection=False" option

-We also recommend modifying the objectQualifier option in the <data defaultProvider="SqlDataProvider"> section. The objectQualifier will be prepended to the table names.  For example, setting it to "DotNetNuke3" will result in table names like DotNetNuke3_Users.  This prevents naming conflict from other tables that you may have in your database.

-To avoid any conflicts, we would highly recommend using a fresh database for the application install.

C) DotNetNuke Setup

- Open your browser and navigate to http://yourdomain.com/ where you install DotNetNuke

- DotNetNuke will setup all the database objects when it first loads.  This process MAY run for several minutes.  DO NOT hit the stop button on the browser

- Remember to set read and write permission as mentioned above, or you might get error when DNN try to run for the first time.