Ok, so at this point you have a test environment set up and you can browse to a version of your current site.

Download the DotNetNuke 2.1.2 source file and unzip into a directory. The source directory contains all kinds of additional files that you don't really need to deploy including .vb files etc. I used a copy of UnleashIt! (formerly known as WebDeploy) from http://weblogs.asp.net/mhawley/archive/2004/09/01/224258.aspx to create a deployable copy of the 2.1.2 source without all of the files I don't need.

Here is a list of the file extensions that I included: (*.asax,*.ascx,*.asp,*.aspx,*.config,*.css,*.dat,*.dll,*.gif,*.htm,*.html,*.jpg,*.js,*.png,*.resources,*.sqldataprovider,*.template,*.txt,*.xml,*.xsd,*.xslt)

Once you have a deployable copy of the 2.1.2 source, select it all and copy it over your existing test site. If you have added anything extra to your web.config file in your test site, save a copy of it first so you can merge that into the new web.config file. For instance, I had some YetAnotherForum.Net section handlers etc. that I needed to merge into the new web.config.

Note: If you have made changes to the default.css or portal.css files under portals/_default, make sure you back them up as well so you can merge that code into the new css files.

Ok, so everything is now copied into where it should be. You should now make sure that web.config is pointing to your test database and that the default data provider is set correctly for your setup.

Now, open your browser and browse to the alias you set up earlier. If everything went well, DNN should upgrade your database to the new schema and you can test out all the functionality to make sure it's all working ok.

Note: I had some troubles with permissions not being set properly on the portals/_default/log folder, so I just gave the ASPNET user the proper permissions and everything was ok.