The core idea is that you’re trying to run/walk every street in your city. Hopefully that’s obvious. 
Your activities sync in automatically as you save them (Runkeeper accounts sync once per day). When they arrive in CityStrides, there’s code to process them. This code compares your tracked GPS data with nearby street data to see what you have progressed/completed.
Each activity shows a count/list of streets it progressed/completed.
If you notice your activities don’t include progressed/completed streets, it may be due to the city not being present in the site. Visit https://citystrides.com/cities and search for the city. If it’s not present, you can request it in Missing/Broken Cities Tracker - Google Sheets
From your profile page, you’ll have a list of activities as well as a list of cities you’ve completed at least one street in.
When you visit a city page from your profile page, it’s your special view - you get lists of incomplete streets, complete streets, and other people (showing how far along they are). This page is super useful … it will show your LifeMap on the map, giving you a good visual of where you have been, and the incomplete street list might be helpful in seeing where you haven’t been yet.
Those are the core/free features. There are many Supporter Features that help even more - here are two of the most impactful, check out the full list in Supporter Features - CityStrides
Node Hunter is a button on the map (magnifying glass icon) that displays incomplete nodes on incomplete streets. If you use it on a city page, it automatically limits the displayed data to just that city’s data (nothing outside its border). This is one of the most important features, since it quickly and clearly shows you exactly what’s not done yet.
Route Builder is a button on the map (squiggly S icon) that lets you plan routes. You build the route by clicking/tapping your starting point, then individual waypoints, and finally your stopping point. Its distance is displayed as you build the route, helping you not plan something that you can’t accomplish. You can save your route, and check a box allowing other people to view it - great for planning group runs.
Still have questions? Post them below & we can get this updated to address those issues.