After uploading mp3 file to your assets folder, click on a copy button (a button with an image of two documents).
Drag and drop "play sound" or "loop sound" block in the workspace, attach a "text" block to it. Then paste the link to the text box.
My object is gone
The preview window displays a content when one or more object(s) are added to the world using ADD OBJECT block. Make sure you have an add object block.
The preview window is black
You need to use a World block to display background in the preview window. World block needs to be attached to an object block to avoid multiple world block to be added to a single world.
Also, check the workspace including behind other coding blocks if there is any extra block. When you have some blocks such as "add object" left on the workspace, that causes the preview window to turn black.
I don't know how to code VR world
Don't worry. We have an interactive tutorial that walks you through the process step by step. You can find it at https://canada.c3d.io/portal.html after logging in.
You can import a 3D model you designed using 3rd party platform such as Tinkercad into C3D. Download a 3D model as a zipped .obj file, drag and drop the zip file to Assets folder of C3D. Click the YouTube icon above to watch a video on how to do it.