If you have poor mathematical skills, yet you're seeking a career path that is math-intensive, then I suggest you find something else to do with your life. Not that I doubt you could, with a enough hard work, teach yourself the necessary skills to do whatever job you have in mind to some degree of success.. but that you are at a disadvantage. Your weakness in math will surely come out in your test results, which are the only objective measure of your ability. If other kids score more highly on tests than you, then it becomes obvious that they are more suited for that particular line of work. When employers request transcripts, they will see that. Competition is something you have to consider. You don't want to choose a career path based on something you're weak out. You want to choose it based on something you're really good at.
Why not focus more on things that you can succeed at with little difficulty?
To answer your question, you'd probably need a collection of textbooks, which will be very expensive. Instead, check out mathTV.com, wikipedia, and sparknotes. Frankly, I don't know what topics secondary math begins with. Are you talking about middle school math?