The pattern calls for cutting squares 3 3/8" from Fabric 1, 2, & 3 and then cutting them in half on the diagonal...*I cut the SQUARES as indicated and then stopped cutting.
When everything was cut I went to Piecing the Block, Step 1.
In this step you will make half square triangles, use the instructions and pair up the appropriate fabrics right sides together. I made the half square triangles by drawing a line from corner to corner and then seam a scant 1/4" away from the line on each side and then you cut on the diagonal line. See picture below for the "pattern" and the direction that they are facing, pay close attention to the bottom brown fabric as well the stripe on the left brown unit is going left to right and the right brown unit the stripe top to bottom. The red units on top you will do that to make one block, the brown units below you will repeat the left diagram four times for each block, and the right diagram four times to make each block. The blue dashed lines indicate the fabric "pattern direction". The green line indicates the line drawn from corner to corner and the red is the scant 1/4" seam allowance. Once you have sewn and cut on the drawn line, press towards the dark and then trim to 3", if you used a scant 1/4" seam you will have a little wiggle room on trimming.
Step 2: Fabric 3, cut (4) of the squares in half on the diagonal to make (8) triangles, assemble as direction.
Step 3: Fabric 1, use the photo below and use the blue line as the cutting line. Notice that the squares have the "pattern direction" in different directions.
Now all of your units are made. Layout the whole block and then piece it together as directed in the pattern. Enjoy the process, you are on your way to making this huge quilt!