Answer 1

Of course it depend on which kind of algorithms you're talking about, but generally algorithms are nothing more than the set of instruction that you give to your program, and the order in which those instructions get done. If I make a simple program that lets you input a number and then shows your number +1, that's an algorithm.

It's all about logic, you don't really need to know anything more than this. But of course the algorithm that you're gonna use changes based on what you want your program to do, and the algorithm that you're gonna make to get it done will be simpler or more complicated based on that.

If the concept isn't still clear to you look it up on wikipedia. You might want to also sketch a little flowchart each time you write a program, so that you can check if you forgot to include anything in the code.