To create your markers you can choose from:
Marker: simple single markers
Marker with Text: marker with text explanation
Image: use of an image as a marker
Marker with Text:
Select the + symbol to create a marker (same step for all marker options)
Type your text
Select Font Size and Font Weight
Select Create to create your marker
Select the link symbol to match the marker with the base picture drop area (same step for all marker options)
The difference on the Image marker option is that you will need to select and upload your marker image