Most Helpful Girl
You should wear a full-body slip underneath that dress. It won't stop the dress from being see-through, but it will help conceal some of the parts that are outlined and provide a more dress-like silhouette.
If the dress is cotton, get a slip made of a silky/satiny material. Read up on what type of acrylic blend you're buying. Some are not really great to use for a variety of hygienic reasons.
If the dress is a silky/acrylic material, you can opt for a cotton-blend slip, which is best for the summer months.