how do i upload a part i make?

[budgetrocketcompany]

I am very interested in making a new part. what should i do? i will be putting it on my craft in KerbalX.

[Vanamonde]

Your post has been moved to the part of the forum where people do that sort of thing, and good luck with your project.  

[wasml]

Unless you're already familiar with the 3D model -> Unity -> Ksp I would start with something very simple like a fuel tank just to get familiar with the tools and with what goes where. After that I would agree with the advice I've seen from a number of modders - do what interests you. Make things for yourself. Of course some things are more challenging than others with fuel tanks occupying the easiest end and (at least in my opinion) wheels and retractable landing gear the hardest end of things. Enjoy!