The focus of the first phase is to organize the project.
Iterations
Usually just one that focuses on establishing the project environment and organizing the team.
Documents
Iteration plan
Create the initial iteration plan to detail who will be doing what in the iteration.
Project plan
Most of this plan should be filled in from the beginning, but a few topics (like handover) might be completed in later phases.
Solution architecture
Write the introduction, which includes the glossary, the design constraints and design principles.
Also start writing about design properties, development and deployment.
Iteration report
Finish the phase with an iteration report that lists achievements and lessons learned.