I feel duty bound to give some advice on a very important point made by Ander Biguri when he explained in a comment to his question that his original code came from MathType. This is a significant point that should be pursued further. I myself have 260 pages of a Physics text that I was writing before I returned to university last year and was turned on to using TeX and then later to LaTeX.
MathType does not produce very good translations of its equations into LaTeX. More often than not significant editing is required. I would only suggest bothering to do this if you already, like me, have a lot of MathType work that needs translating. Personally, I do not do any new work with MathType. As a maths student and teacher, I now do all my assignments, articles, presentations, whatever with LaTeX. It's well worth persevering with LaTeX.
If you are starting out learning LaTeX and will continue to do so, you will find that it can solve virtually any maths typography problem out there. There is a good unofficial manual online at LaTeX Reference Manual and you can download a pdf version. Starting with a document like this you can discover all the usual LaTeX commands and when you get stuck ask a question here.