If you have created an account on SlideME as a normal user, but wish to upload applications as a developer, do not attempt to register a new account. Instead, you can convert your user account to a developer account.
Click "My Profile" on the right-hand "My Actions" menu of the website. Then, at the top of the page click "Edit". Scroll down until you see a section such as the one below that will allow you to convert your account:
Are you an Android applications developer? Click here to setup your developer account!"