Use the Change Style option for individual layers to change its symbology (e.g., color, transparency, symbols, data classes, etc.)
Configure pop-ups for your layers. This feature is located under the ellipsis menu (...) for the layer.
Use the Legend tab to preview the legend for your map. You can rename layers under the ellipsis menu for the individual layers.
Save your map. The title and tags fields are required. Your map and layers will save to the My Content section of ArcGIS Online. Remember to save often. ArcGIS Online requires an internet connection so you don't want to lose any work if your wifi signal drops, etc.
The ArcGIS Arcade scripting language provides a wide range of options for customizing map symbology, pop-up windows, and more. Check out the ArcGIS Blog for additional posts on how to use Arcade expressions in your map.
This blog is an excellent resource for keeping current and for learning how to use different features within ArcGIS.
Before you leave Brandeis
Transfer your ArcGIS Online content before leaving Brandeis
If you'd like to retain access to your ArcGIS Online map content after leaving Brandeis, you will need to transfer your maps, web apps, and associated data to a non-Brandeis account. Here are some methods for preserving your content:
After creating an ArcGIS Online Developer account, you can use the “I Want To… Copy Items…” tool in the ArcGIS Online Assistant to transfer your items from your Brandeis account to your Developer account.