In various agile methods, there is often a concept of an initial increment (in Scrum, a sprint) that is designed to set up your project. This is often called Increment Zero (or, in Scrum, Sprint 0).
Such an increment is used to set up the team's environment - set up your development, test, and production environments, configure your supporting tools and scripts, and establish your working environments with burndown charts and backlogs. If anyone on the team is not familiar with the development tools being used, this is where they learn the basics to function and begin producing output in the first iteration.
Along side this, you'll often be starting to write your first user stories and prioritizing your product backlog, since there isn't a sprint backlog at this point. Whoever is the Product Owner will be devising stories. If this person is new to Scrum, they would be learning how to write good user stories that the team can work with, as well. Don't emphasize getting all of the stories, but you'll want enough to kick off the first development iteration.
Different teams handle Sprint 0 differently. Some might timebox it at the same duration as any other sprint. Others might make it a little longer or a little shorter depending on the needs of the team. Since this is your first attempt at Scrum, I might make it longer, especially if you have a shorter iterations as part of your development cycle. If you are planning on two week iterations, make it 3 weeks.
As far as formulating the tasks, I wouldn't necessarily formulate them as user stories. You could, from the perspective of team members and various roles (Product Owner, ScrumMaster, developer, tester, designer, technical writer, and so on). However, Sprint 0 is for the team, not for the customer or the user. A simple list of tasks and activities would suffice.