Sew your border print quarter-square triangles to the background quarter-square triangles. There will be four pairs of these. They comprise the center of each side of the block. Then sew each joined pair to the opposite color of the four remaining half-square triangles.
Throughout all of this, you have not needed to match up any stripes.
That comes next!
green sewn to white
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all quarter square triangles lined up to be sewn to half square triangles
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