Add an existing solution to TFS 2013

This post assumes you have a TFS server configured.

First you will need to create a TFS project to hold your files.

1. In Visual Studio 2013, Team Explorer, click the navigation drop down bar and select Projects and My Teams and then choose Add New Project.  You may need to be a collection administrator to do this.  Browse here https://<TFS Server>/tfs/<Collection Name>/_admin to add a user to this group.
2. A wizard will appear that will walk you through all of the options.
3. The most important option here (and the most difficult to understand) is choosing the process template.  Essentially, you are choosing what application lifecycle management style you use while developing software.  I chose Scrum because it's something that I'm interested in and it's the default choice.
4. You'll also need to choose a version control system, Git or TFVC.  With Git the repositories are stored locally and with TFVC, there is a single version of the truth on the server.  TFVC seems more appropriate if you're going to have a full blown TFS server.

Next, add your solution to the new project.

1. If you don't know your branching needs yet, then don't create them at this point.  However, more than likely at some point, you will want to create branches.  To prepare for this possibility always put your initial files into a folder called Main.
2. Map the new project to a local workspace.
3. In Source Control Explorer, right click the project, and choose New Folder and call it Main.
4. Check in this new folder.
5. In File Explorer, copy your code into the Main folder in your workspace.
6. In VS, open your solution from the Main folder in your workspace.
7. Right-click the solution, and choose Add Solution to Source Control.
8. Then Check In everything and you're done.

http://msdn.microsoft.com/en-us/library/vstudio/ms181384.aspx