Need a Math Editor to integrate to my application written on C# to be able to write math formulas. Can someone help me with this please? Some open source code will be great! Tell me steps, that integrate your suggested application to my application.
Why don't you then just use Equation or MathType in our program. I'm sure they have components that you can use. If you want open source I recommend using Math from OpenOffice.org (http://www.openoffice.org/product/math.html)
I would say the best solution is to let the user write the mathematical expressions in TeX syntax, possibly including TeX renderer that updates as you type.
You should check out LyX - it's an open source (GPL) document processor that uses LaTeX. I'm pretty sure (but not 100%) that it displays the text as you write - and the "steps, that integrate [my] suggested application to [your] application" could possibly be found in the source code ;-)
Another thing to check out is LaTeXiT (if you have acces to a Mac). It uses LaTeX to write equations. It's not open source, but maybe it'll give you some ideas.
Best of luck!
Perhaps you could use one of the MathML compatible editors on this list? Is your C# application a web-based application or a desktop app?