When you press the digital crown on an Apple Watch it displays the apps installed on the watch. By default they are a group of small icons which are sort of fun to look at, but are very difficult to navigate, because they aren't in any particular order, and don't have the app name displayed.
You can re-order these using the Watch app on your iPhone, but I suggest viewing them as a list instead. There are two ways to do this, one on the phone, and the other on the watch:
On the watch
Open the app list by pressing the digital crown. Long press on this screen (press for about a second). Tap "List View" in the menu that appears. You can also tap "Edit Apps" to make certain apps not appear in the list.
On the phone
Start the Watch app. Tap "App View". Choose "List View" The changes should appear on the watch.
Using the List
After changing to List View, open an app like this: Open the app list by pressing the digital crown. The apps should appear in alphabetical order. Scroll up and down by turning the digital crown. Tap the app you want to launch.