To register a team for a NH-DI regional tournament, use the menu pick teams=>register for regionals.  This will list all the teams associated with your account (see example below).  Click the pencil icon to the left of team number to start or continue the registration of that team.

Clicking on the pencil icon should display a page similar to the one below. The team your are registering is just below the green menu bar.  Below that are a set of tabs (My Teams, Summary, Vital Info...) each being a step in the process.  The steps are in a logical order (left to right) however you can move to any step by clicking on its tab.  For example if you want to pick a different team, click the My Teams tab. Each of the steps is explained in a sub-topic to follow.