Open Blender and import your 3D models
When you first open Blender there will be three items in the scene: a camera, cube, and lamp. I just delete all three of these items by selecting them, right clicking, and clicking delete.
To import your 3D models, at the top of the window click File > Import > and choose the file type you will be importing (in my case it will be .ply files).
Navigate to where your files are, select them, and click the Import button in the top right.
Your files should appear in the top right scene section. You may need to zoom in or out and move around the scene to find your objects.
My scene ends up looking something like the image to the right ->
My 3D meshes are already aligned to each other, so it is important that I keep all of them selected at all times and perform all transformations on all objects at the same time.
If the objects you are importing are already aligned where you want them to start in relation to each other, make sure keep all of them selected. You will know if an object is selected if it has an orange circle behind the yellow triangle icon next to the name. You can use the shift button (on a mac) to select more than one object at a time.
On the bottom toolbar, click the red, blue, and green lines to open up more options for transformations. Change the drop down option to Global and click the button with the arrow. This will make moving your objects much easier, You can mess around with the other options, but I find this one the easiest to work with.
Adding color to your objects
I have 20 different objects and they are very close to each other. I find it is easier to move them around if they are different colors.
Choose one of your objects. Select it and only it in the top right scene menu.
In the small toolbar below the top right scene menu click the button labeled Material. It is highlighted in the image to the right. Then click the New button.
Below where it says Diffuse, click on the open, white colored spot. A small menu will pop up where you can choose the color or enter in RGB, Hex, or HSV values.
There are lots of other color and lighting options in this menu that you can play around with.
Now go through and color all of your objects.
Placing animation keyframes
Here is a nice, simple tutorial video on animation in Blender.
To reselect all of your objects (meshes) you can go to the bottom toolbar, click Select > Select All By Type > Mesh.
Now, in the toolbar where you selected Material, click on the camera button. If you scroll down you will see a section titled Dimensions. Here you can change the number of Frames and Frame Rate. I'm keeping a frame rate of 24 fps, and I want a roughly 4 second animation so I've changed the end frame to 100 (4 X 24 = 96, close enough).
On the bottom of the window is the Timeline window. Here is where we will interact with the frames of the animation.
Make sure the green line is at frame 1. You can click in the timeline or move the arrows/time in the box that says 1 in the image below.