How do I embed textures in .dae with Blender?

[Henchman800]

The DAE (collada) format doesn’t support embedding textures into the file itself, you’ll need to make sure filepaths are referenced using a relative path (i.e. make sure the references don’t give a complete path like “C:\Users\etc...”) then provide the textures zipped with the model. Blender’s DAE exporter should have an option to set texture / whatever paths to relative instead of absolute.

Alternatively, you could export a binary FBX format model with the textures embedded into the file itself.

Thank you very much for the quick answer! My .fbx uploads have been rejected, though.
I'm still not getting the .dae export done correctly...
Can you please give me a step by step guide? I'm using blender 2.8 and I only get these options when I want to export .dae files: