If you can't code at all, you can take the easy way out and use synthedit or similar tools. Disadvantage: The plugins waste tons of resources (read: they are slow and big).
So the real options are:
1.) If you're a delphi coder, use the translated vst sdk (you can find all the links at tobybear.de)
2.) If you're a c++ coder, just get the vst sdk from Steinberg.
In any case: Read the sdk docs, read tutorials, look at example code, learn DSP basics. Oh, and have fun of course.
http://tomaes.32x.de [new media experiments]