How to find syntax errors in html?

Colanth is right, HTML will not help you here. Try taking a brief beginners online programming course in java or python or some language good for beginners that has a free compiler, python has IDLE and I use eclipse for java, after a few videos you should have the hang of it enough to do a simple program that asks the user to input numbers that uses them in an equation. youtube has videos from MITOpenCourseware and Stanford programming methodology is a good video course to watch. If you've done all of that and still don't understand it, then programming may not be for you.