UNFORTUNATELY, the park officials of the park by my house have taken down the tennis court net, which isn't good, because I can't play tennis anymore. I really wanted to try out my slice serve, because, since my lesson a couple weeks ago, I haven't had a chance to try it.

I finally understand how slice serves work.  You put spin on the ball, and that spin slows it down, which helps you make the serve in.  If it's a flat serve, you have to get the angle perfectly, but it's much more powerful.  That is why you use slice serves for you second serve.  

Sadly, I haven't had a chance to practice my serves yet, thanks to some dumb park officials who didn't care about the public's interest. :(