A combination of Power BI automated organization, user tagging, searching, and sorting allows you to quickly find what you need in Power BI service.
Power BI service organizes your content in several ways. First, it separates your content into dashboards, reports, workbooks, and datasets. You'll see this organization on many of the Power BI screens. Next, Power BI service classifies your content in ways that make it even easier to find what you need, quickly. Take a look at your left nav.
Content that you create for your own use is available in My workspace, content that you create and share with a group is available in an app workspace, content that you want to access quickly is saved in Favorites, content that is shared with you is available in Shared with me, and your last-viewed content is also available in Recent.
For more information, see How content is organized in Power BI service
NOTE: One additional way to organize your content is to pick the one dashboard that you expect to view most often, and set it as your featured dashboard. Each time you open Power BI service, this is the dashboard that will display first. To learn more, see Featured dashboard.
Do you have a number of dashboards and apps that you visit often? By setting them as favorites, they'll always be available from your left navbar.
Working with favorites is described in more detail in the article Favorites in Power BI service.
A workspace has four content tabs: Dashboards, Reports, Workbooks, and Datasets. Each of these tabs contains a search field and a sort button. When you're starting out with Power BI service, you might not find these helpful because you'll have only one or two items per tab. However, over time you may may end up with long lists of content. Use searching and sorting to easily find what you need.
Enter a search term to find a match on the current screen
Select the sort button to display options for the current page. The options are to sort by name or by owner.
More questions? Try the Power BI Community