Media Content, both folders and items, are ordered both in the Admin Portal and the Webapp/App by Alpha Numeric values.
If you wish items to appear in a particular set order, the best practice is to develop a numbering or lettering convention at the start, such as:
1. Media Item 1
2. Media Item 2
3. Media Item 3
etc, with the numeric value at the start dictating the order.
After you upload, build or create content in the Admin Portal you will need to make it active in order for it appear on the app for your learners or users.
You can do this in one of two ways;
Make it active in the Settings or Content Details
Make it active in Drive
If you are building your own content such as a course, content page, quiz, form or dashboard, whilst you are in the builder, click settings and choose to make the content active. (as below)
Alternatively if it's already built, simply select the content in the list in drive, and the content details shortcut will appear to the right of the screen. Simply switch to green, making it active. (as below)
If you have a number of content items to activate, activate them all at once by holding down the Shift key and selecting multiple content items or folders. Or hold down the Command key to select individual items in the list that are not beside each other. Now click the activate content icon in the tool bar beside the Add Content button.