salad

Hi everyone, I am new to 3d printing. I have this problem. When trying to print this small part(55X35X5 mm) https://www.thingiverse.com/thing:31436 the top and bottom layers look terrible. You can literally see right through the holes to the other side of the part. I think the problem is in the cura settings but I can' find the right one. Basically all of my prints have this problem. Does anybody have any idea what is causing this? Thank You for your help