We are now ready to make a new web application and site collection which we will need to match closely to the original SharePoint 2007 server. In the SharePoint 2010 server:
Open SharePoint Central Administration | Manage web applications
Click on New
Enter in the details for the web application using the document from the rule Do you document the details of your SharePoint 2007 web application?
Go back to SharePoint Central Administration | Create site collections
Fill out the form to create a new site collection – the only option that is important here is to create a site collection that matches the site collection you will be migration. Eg: If the site collection you are migrating is a Team Site, make a site collection that is a Team Site.
Note: The rest do not matter as they will be replaced when you restore the database from SharePoint 2007.