do you have a compass? if not, you will need one. using a ruler or tape measure open the compass to the desired radius. Using a square mark your center on the stock.
looking at your picture above, say for the 3-3/8 radius, from your finshed line come down 3-3/8 and from the end come over 3-3/8. There is your center point. put the point of the compass on that center mark and draw your radius. do the same for each of your curves. Cut out your curves with a jig saw or band saw next to the line then sand to the line.
Welcome to the family!!
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If it isn't critical the radius be exactly as drawn (I'm guessing it's not from the layout)I usually look for household items that approximate the diameter I need, and use them to draw the arc. For example, a 5 gallon bucket I have is 10 1/4" across on the bottom. That would give you 5 1/8" for the large arc. A gallon of paint might do (don't have one handy to measure) for the 3 3/8. Lay out the start and stop points and set your pattern (whatever it is) to touch both and draw it out.
Welcome, This may help:
I do have a compass but for non-critical things, do as Fred does.
Any sufficiently advanced technology is indistinguishable from magic.
- Arthur C. Clarke
If its a pain to use the compass because there isn't any material at the center of the circle I've laid it all out on stiff cardboard first and then cut along the lines with a razor knife and used the cutouts to transfer to the finished stock. This has the possible advantage of also giving you the option of more alignment points as well for the "on the stock" layout which sometimes matters.
I do what Fred suggested a lot as well