Well, I can't give you as much help as I'd like, since I have not use Port's exporter yet and I currently still use Blender 2.49 for mods.
As far as I'm aware, armature/skeleton animations are not supported by Port's exporter, so you will have to use empties and animate those (you parent the mesh to the empties).
As for animating within Blender, you'll want to have the action editor visible so that you can see the keyframes of your animation (set a window to the Dope Sheet and then from within there, change the dropdown menu to action editor, as by default it is set to Dope Sheet).
It can also be nice to have the timeline window visible.
Press I (with mouse over the 3D view) to add keyframes. Normally you'll only need to use LocRot (location and rotation) for Blockland animations.
The left and right arrow keys will move the selected frame of the animation around, and you can also drag the green line around in the action editor to move the frame around.
And press Alt+A to preview your animation.
You might want to ask Trogtor for further information, since he is a very skilled animator and he has used Port's exporter quite a bit.