On leaving the ferry, cross the road, turn right and follow the road as it curves into the central square. Once on the square, you will see a road ahead of you leaving the square and running between the Artemis Bakery on your left and the Piraeus Bank on your right. Simply follow the road for about 50m. You will then see a narrow road hiving off to the left and running almost parallel to the road you were on. A sign at this point will indicate the Hotel Semiramis. Follow this road for 20m. The hotel will be on your left.

You can see also on the below link to have an idea!

http://www.cyclades.mobi/milos/semiramis_en.html