How to Plan Iterations
You have created a Release with Iterations, now it is time to plan the Iterations you created.
Navigate to the Iteration Plan area.
On the left you’ll see a Backlog. Backlog shows all User Stories that are not assigned to any Release or Iteration. You can check the Bugs check box to view Bugs in the Backlog.

User Stories and Bugs can be filtered by various parameters, such as Priority, Tags, Custom Fields, etc.
On the right, you can view the two closest iterations. They may be current and next iterations or two future iterations. You can use the drop-down list to select the iterations you want to plan.
Use drag and drop to assign User Stories and Bugs from Backlog to the selected Iteration. You can also re-assign User Stories from one iteration to another.

You can view the iteration velocity on the screen and control the iteration scope. There's no need to have an exact velocity match; it is more about team commitment. For example, let’s say you have an 80 points velocity, but the team commits to ship 100 points in the next iteration. If this is the team’s decision, the Scrum Master should not interfere, but just accept it.
You can view iteration velocity on the Iteration Plan and control how much work has been already assigned to the iteration.
Move the mouse cursor over any User Story or Bug and notice a small [ i ] icon. Click it to view some additional information about a User Story or Bug:

You can navigate to the full view or click Edit to change the item.
Learn how to use Batch drag & drop and prioritize User Stories and Bugs.