Not all seams are straightforward straight lines. Sometimes you will find three fabric edges meeting at one point – for example when sewing hexagons together – and for this you need a Y seam or inset seam.
I have chosen three fabrics here with a definite wrong side and right side for clarity.
Until you are confident with inset seams, it is probably worth making a mark 1/4″ from the edge on the wrong side of the fabric. This is because all the seams must start and finish 1/4″ from the edges of the fabric. Begin by sewing together two of the hexagons (apart from the 1/4″ at each end). Press the seam open.
Place the brown and yellow hexagons with right sides together. Sew the seam from 1/4″ away from the edge to the red/brown seam line. Stop with the needle down in the seam line. Lift the presser foot and reach around the left of the needle to grasp the yellow hexagon. Pull it round towards the front so that it now lies underneath the red hexagon. Line up the edges, swivel the red/yellow hexagons so that the presser foot is now following the next line of stitching and continue sewing to 1/4″ before the end of the edge. Take the fabric out of the machine and press the seams open.
The video should make it clearer: