Do I upload both frames here?
No. Describe them and copy the prompt. Attach the images in your model.
You describe the start and the end. The prompt asks for one motivated move, not a collage.
You still supply the two images to the model. This page writes the words.

Nothing leaves your device unless you paste the prompt somewhere else.
Write the brief
A match of shape, a whip, or a push through a doorway. “Seamless” alone is a dissolve the model invents.
If you cannot say what each frame is, the middle will be a third place.
Match cut, whip, or a move through. Not all three.
Start readable, travel, land readable. A blur with no landing is a mistake.
Use these shapes when your two frames rhyme.

Shape match
Hover · demoA circle becomes a circle. A cup rim becomes a moon.

Whip
Hover · demoSpeed hides the join.

Push through
Hover · demoA doorway or a light that both frames share.
Subject, place, and the shared shape or direction.
Match, whip, or push. Write it in the form above.
A transition prompt without the end frame is a guess.
The middle is where models freestyle.
A dog and a spreadsheet have nothing to match.
The fix: Cut. Do not ask for a morph.
Match plus particles plus a logo sting.
The fix: One device.
Six seconds of travel invents a hallway.
The fix: Two to four seconds, then land.
No. Describe them and copy the prompt. Attach the images in your model.
Use a whip or a plain cut. A match cut needs a shared shape.
One join at a time. Chain them in the editor.
Write the start, write the end, name the device.