Learning to control the spin of the ball is one of the most important things you can do- if you want to advance your game.
Nearly every shot in tennis has some spin imparted to the ball- topspin, underspin, sidespin- to a greater or lesser degree- depending on the situation and what you are trying to do.
So, first of all, I would caution you against trying to hit great looping topspin shots-- just because you can. Every shot has its uses (and spins) and should be chosen accordingly.
If you could hit exactly through the center of the ball without creating any spin, then the only forces working to bring the ball back into the court would be gravity, the speed with which you hit the ball (determining its time in flight), and the height over the net that you hit it.
With no spin, the higher over the net you hit the ball, the slower you would have to hit it- to allow time and gravity to bring it back down. This would be sort of like a "moonball"--a slow ball that just arcs over the net without any special force or spin.
Topspin, creates an imbalance of pressures on the ball's surface, causing it to dip down into the court. If you have the power and timing, this spin can be quite effective for a variety of purpouses.
To create the topspin you must drive THROUGH the ball with your racket traveling from low to high. The greater the high to low angle, the more spin. But, the more spin you create, the less forward speed/momentum you will have.
And, yes, you will strike the ball with the racket face vertical (or very nearly vertical) to the surface of the court and facing the direction where you want to drive the ball.
If you "open" your racket face and hit the ball hard, it will be like what happens when complete beginners go out and swat at the ball-- the ball will fly up, over the fence, into the parking lot, and under the car belonging to the crankiest old man in town.
So, since you seem to be just learning the basics of the game, I would advise starting slow. Try for a minimal amount of topspin at first, keep the ball in play while trying to move it about, or place it excatly where youwant (as much as possible). As you become proficient, then try to vary the amount of spin and speed with which you hit the ball, making your arc higher or lower, the ball land deeper or closer to the net. This way you will learntocontrol the ball to suit the situation.