Linen muslin or linen weave are extremely delicate fabrics that do not bear unnecessary pressure on the seams and have no stretch ability. Linen is designed to be worn loose on the body.
Your linen garments are best washed in warm water by hand, or on a gentle machine wash using a mild detergent to safeguard against fading of colours and shrinkage.
Linen should be dried in the shade. Overdrying will result in your linen feeling stiff. Pegs can cause marks, and hangers can cause the garment to go out of shape. Linen is best dried laying flat.
You may iron or steam your linen to remove creases, but it is not required. The distressed and crumpled appearance is intended and should not be interpreted as a defect.