V2 does not support importing webparts that were created using the Digital Dashboard Resource Kit 3.0 (which is the DDRK in Portal Server 2001. Unfortunately any webparts that you made and customized are usesless now and you will have to start over. In version 2 there is a new feature called Add Web Parts in the Edit Page view (see the help file for details). You get there by selecting Edit Page on the left then (very confusing) you use the menu on the right called Modify Shared Page and click the drop down arrow and select Add Web Parts. From there you can choose Browse, Search and Import. As far as making new webparts or adding them like you did in 2001, I believe, not sure yet, that you simply drag and drop you webpart onto your Portal page. You have to go into the "Design This Page" view which is part of the Add Web Parts menu mentioned above. Weparts are expected to be coded out of Office 11 now rather than modifying the script/code within the Webpart properties (like in SPS 2001) I am very frustrated about the "NO MIGRATION PATH" that MS conveniently dropped the ball on. Talk about alot of work that is worthless now....that is what happens when you constantly try to do Marketing rather than R&D!! Rather than use Building Blocks MS again has taken a house made of straw and decided to rebuild it out of bricks. The new version is stronger but starting over is going to be a chore.
Good luck.