If it's a corporation (and a sole proprietorship, an LLC, or partnership), it MUST have at least one shareholder by definition; corporations are owned through their shares. If you are the only owner, then you are the sole shareholder and you own 100% of the shares. Therefore, use a corporate form, but if you're the only owner, list yourself as sole shareholder owning 100%.First though, check the paperwork forming or incorporating your corporation and check also to see that it is registered; if you haven't receiving anything making clear that you are the sole shareholder (and indicating, among other things, how many shares you own) it's not impossible that either the company was not in fact incorporated or that it was set up under some different form (e.g. as an LLC).