You can certainly choose a CMYK or HSL dialog in the fill and stroke and all colour pickers, but it converts all colors to 8 digit hex as you willl see in the bottom of the picker. Since RGB and CMYK spaces are both device-dependent spaces, there is no simple or general conversion formula that converts between them.
Fold and press the sides. Working on either the left or the right side of the fabric, fold the fabric over 1.5 inches and pin. Do this the entire length of the fabric and then use your iron to press in the crease. Now fold that edge over another 1.5 inches, pin and press. Repeat that process on the other side of the fabric.
This will hide the raw edge of the linen. Pin this double fold into place. Top stitch the fold down. Repeat these steps to hem the opposite side of your linen and make sure to fold the hem towards the same side as the first fold. Repeat the same process to hem the two remaining sides. Fold towards the same side for these as well. You can cut the tip of the corners for these sides to reduce the bulk.