The coffee table base you took home after the Basic Carpentry Workshop needs a top.
You could go for a glass top or a wooden top. The glass top can be fixed to the base either with suction cups or pasted on to metal discs which in turn are screwed on to the wooden base.
A pinewood top will also go very well with the pinewood base.
Before applying stain to pinewood, apply a coat of mineral oil/kerosene to condition the wood. This will make it absorb stain and polish uniformly. Staining and polishing done without preconditioning the wood would produce a patchy finish. After pre-conditioning the wood, apply stain to get the required shade and follow it with 1-2 rounds of sanding sealer, followed by a sanding with 220 grit paper. After this, apply 2-3 coats of wood polish with a muslin cloth.