As you fully integrate Teams and move and store more of your files in Teams, it's important to be able to find those files easily. This is a really simple process but for most users, is a huge time saver as well as a way to more fully integrate Teams.
One of the best ways to find files stored in Teams is to use the SYNC feature in the channel of a team. This features let's you perform a one-time sync which allows you to always have access to the files you share in Teams from File Explorer. When you have your Team's channels synced to File Explorer, it's easier to save files when you're in an O365 app like Word or Excel.
You only need to sync one time and it will remain synchronized in File Explorer indefinitely.