Many Foldit design puzzles let you insert and delete segments. Adding or removing segments may help you find a better shape for the protein or meet the conditions of a specific puzzle.
This puzzle has a light-colored helix in front. You can insert segments into this helix.
A thin red line at the right end of the helix is a constraint. Constraints work like bands, pulling things together. Unlike a band, you can't delete a constraint. Design puzzles use constraints to keep parts of the protein from moving around too much.
Constraints often appear in puzzles like this one, where only part of the protein is available to design. Other design puzzles let you build an entirely new protein from scratch, and don't have any constraints.
The first step is to select Design Mode from the Modes menu. Then pick a spot in the middle of the helix, and right-click (or control-click). An insert/delete wheel menu appears. Try "Insert Two Between". The additional segments should make the constraint much shorter.
After inserting the segments, try wiggle. After wiggling, use Mutate from the Actions menu (keyboard shortcut "m"), then wiggle again. This should be enough to complete the puzzle. As usual, you can try mutate, shake, and wiggle for an even higher score.
During the initial wiggle, you may see several other red constraint lines appear and then disappear. These constraints are helping the protein keep its shape. The initial constraint gets shorter as you wiggle, but it doesn't disappear entirely.
After adding segments to the helix, you'll also be able to delete segments, again using the insert/delete wheel menu. You experiment to see what happens when you add segments at different spots.
One of the help popups for the puzzle says "the blue blinking segments will show you where it will appear" when you add a segment. There are no blue blinking segments here, but they do appear in other cases when inserting or deleting.