This puzzle introduces the move tool, which lets you move pieces of the protein around. In this puzzle, the protein happens to be in two separate pieces. With the move tool, you can move the pieces around separately.
This puzzle has a guide, like the previous Quest to the Native puzzle. The lower piece of the protein is not aligned to its guide.
The upper piece of protein is aligned to its guide. It's so well aligned that you really can't see the guide.
To use the move tool, click anywhere on the lower piece of protein. A purple cross and a curved purple arrow appear.
To move the lower piece of the protein, right-click (or control-click) and drag on the purple cross. In this puzzle, it's best to move the lower piece straight up the screen until it matches the guide.
Tip: just dragging on the purple cross, without right-click or control-click, tilts the protein, but doesn't move it through space. Shift-click and dragging on the purple arrow zooms the protein in and out. The curved arrows tilt the protein right and left in the direction you're looking, and work the same way regardless of key combinations. The curved arrows are useful for fine-tuning the position.
If clashes appear between the two pieces of protein, use the move tool to move them a little farther apart.
Tip: rotating the protein by dragging on the background can help. The usual method is rotate up or down or right or left by about 90 degrees, check and adjust the alignment, then move 90 degrees in a different direction. Repeat as needed. The goal is to see how well the protein is aligned to the shadow guide.
Once the alignment looks good, shake and then wiggle to finish the puzzle. If you wiggle without shaking first, the two pieces of the protein will fly apart, and you'll need to move them back and try again. (Or, reset the puzzle.)
Technical stuff: the move tool is important. This puzzle is relatively easy, since moving the lower piece straight up the screen in usually enough.
In this puzzle, the protein is in two pieces, known as chains. Proteins consist of multiple chains, although proteins of this type are rare in Foldit puzzles. In some multi-chain proteins, each chain is the same. Foldit symmetry puzzles feature this type of protein.
In Movin' Along, the two chains are actually identical, made of the same amino acids. The keyboard shortcut shift + a shows all sidechains, which makes it easy to see. The "head" of one chain is next to the "tail" of the other chain when the puzzle is solved, but you can use the move tool to put the chains side-by-side in the same direction for comparison.
Other proteins have chains with different amino acids and different shapes. Insulin is a good example. Foldit has an "insulin mutant" revisiting puzzle which contains two different chains. See Puzzle 1501 for images of the most recent "revisit" to this puzzle.