By Tuesday, you mean tomorrow ?
If yes, I can not help you, sorry. If next Tuesday, you got a lot of work to do.
I’m a beginner too so others might have better proposals.
I’d say for a start, go read this tutorial here:
up until section 2 -> Using bones.
Definitely do this until you are able for basic controls, e.g. move things around, understand the materials and textures buttons, use B, R, G, S, Tab, Ctl-Click keys automatically, etc (those are used to select/move/rotate/ scale the whole model or parts of it when we edit it). Space brings up a menu to create new things. Tab switches to edit mode. Perhaps you will not require to edit meshes for this project though…
I don’t think it is easy to find a .blend rigged free dinosaur in the Internet.
But what you can do is find a .3ds model, import him, and put bones and textures
on him anew. There are threads here about importing .3ds models (you basically need
to remove double vertices, and some other things that I don’t remember). Bones should
be quite easy in theory, if you have done the tutorial above.
Then you need to insert your video as a background image, align the dinosaur and camera
so the angle matches the video, and perhaps insert a plane under the dino that only receives shadows,
so that his shadow is projected on the video “street”. Shadow of the dinosaur on the footage
will greatly enhance realism of the scene.
Then you need to insert the same video as horizon. Create a cube somewhere and apply the video
on the cube as a texture. Put the cube away from the camera (we just need the texture assigned somewhere,
this is why we use the cube for. But its not needed in the scene of course). Then go to Buttons, World button, insert video as image texture, click Hori button (for Horizon). Now this should render the video as background.
This should take a few minutes.
And last you got to animate it. You will need the Timeline and “I” key, to record various poses of it in time (the program will automatically render the in-betweens). You need to be in “Pose mode” to move the bones.
Well those are standard things, it’s just that the interface is not standard. Here is an example (what I would do):
Right click on the cube, Delete, confirm.
Download some .3ds dinosaur
File->Import .3ds -> select dinosaur file
In the camera window: View background image -> Select -> Select the background video
(but Im not sure it recognizes mp4 so you might want to convert it). Press Auto-Refresh and
make it use all the frames of the video. In the Buttons window at the bottom, select the Timeline and match the animation frames
with the video frames number. Move the slider and see if the background image changes.
Right click on the dinosaur, press G and move him inside the camera view. Press R to rotate him, S to scale him.
You might need to move/rotate the camera as well ( you can select the camera in the other views, it is a visible object).
Put bones in it like the tutorial.
Create a plane (Space -> Add -> Plane) under the dinosaur. On its material click OnlyShad, so that the plane is not drawn,but the shadow of the dinosaur on it is. Press F12 to render a couple frames and see what happens.
Gee this has gotten too long. I hope it helps, good luck mate !!