I want to be an expert in programing,which topics in mathematics and further maths should i take more serious? I would also like to know which programming language to begin with.

In most cases, the amount of Mathematics you need will depending on the kind of computing you want to do -- what Mathematics teaches you (that's non-trivial) is logic and structures which comes in very handy when you're trying to break down a problem and make head way.

You cannot be an expert programmer, no one can, everyone keeps learning, and learning, which make my next point. There is so much to learn and when you start you start seeing that the more you know, the more you discover you don't know, you continue to learn. And of course, be read to learn for yourself, school is B#llSh#t. A lot of B#llSh#t.

That said, after you've gotten your algebra and geometry straight, an interesting area of mathematics that will help a ton is "Discreet Mathematics : http://en.wikipedia.org/wiki/Discrete_mathematic )" It is the core of anything you do on computing, hardware or software al-ike.

Don't be deceived though, being good at DM wouldn't make you a super programmer, it will just allow you see problems different, as you might have noticed the idea really is, if you want to be good at programming, you have to program, read the 1st chapter of this book and see if the field is for you: http://learnpythonthehardway.org/book/intro.html