You can add suggested places by clicking on the "+" icon for adding products and services in the editing area of your trip:

Step 1 - Click "+":

Step 2 - Click on "SUGGESTED PLACES":

Step 3 - Choose between existing locations in our database or those created by you in the "LIBRARY" tab:

Note: In order for this function to be available, remember to enable "SUPPORT LOCATIONS AND ACTIVITIES IN THE DESTINATION" in " TRAVEL CONFIGURATION":