Hey Heather,
You have come to the right place!
First question, how many squares wide and long is this quilt going to be? That will impact the yardage.
To get total yardage (roughly)
For the black fabric (in the picture - Color 2), take total blocks and divide by 5. Round up. Multiply by 7". That gives you how long to ask for.
The way I came up with that, each block starts as 6 7/8". For ease, I rounded up to 7. I then said on average fabric is 40" wide, so the most blocks I could get from 1 7" strip is 5 (=35"). You can possibly get 6, but I wouldn't assume that. So then if you had 10 blocks total in the quilt (waaay too small), you could get those 10 from 7" x 2 = 14" cut of fabric.
Does that make sense?
Color 1 - red - needs 1 3.5" square. 40" total in the fabric = 11 blocks per fabric. Total blocks / 11. Round up. Multiply by 3.5". Get that many inches cut
Color 3 - 4" x 11" strip. Hmmm... total blocks / 10 - round up. Multiply by 11" (I'm cutting it so it's an 11" piece cross cut into 4" strips. Would work the other way).
Color 4 - 3-7/8" square - total blocks / 10. Round up. Multiply by 4".
Phew! For all of those, I would then add 1/4-1/2 yard for extra/mistakes/etc.
If you reply with final quilt size, I can help with borders and back too.