3) how can your microcontroller make the buzzer sound?

Even this task is much simplier than it sounds: Normally a 'buzzer' is a part which needs only be activated by a static level. If, on the other hand, a piezo is used, this one needs the periodically toggling of input voltage.

So, all Dee has to do is to make some very simple input and output instructions in C. And if this presents a problem to him, then he cannot be helped. Sorry, Dee, but it's only a question of half an hour learning or reading by YOURSELF and is not the classical issue for getting help here.

Only if you have made a mistake, or something does not work as intended to work, then you will get help here. Assume you have wrote such C program and it does not work. Then you can publish it here and we will have a look. But the basis of this procedure is, that you are also willing to do YOUR part! And your part is, at least to have a look into a tutorial about C programming and TRY to find a solution by YOURSELF first!!

Heaven, when I started to learn electronics, I did not have this internet. Did not have good books. Did not have good teachers. Everything I learned was a struggle. Big companies I contacted to give me datasheets, laughed about me. Told me, they do not have contact to private persons. I had to beg for alms by them...

And today, you lazy bone are not even willing to spend only half an hour on reading a simple tutorial? Everything is spread before your eyes and you are not willing to spend any energy????
Heaven, what's that for a pampered generation...

Kai