I have used PhoneGap to upload the same HTML/CSS code to Google Play and App Store.
To upload to Google Play, you'll need to sign up for the developer account. You'll download PhoneGap and the Android Developer Tools + Eclipse to put the code in its final form as a signed apk file. You'll fill out the app page details in your Console page and upload the apk file.
To upload to the App Store, you'll sign up for their developer account. You'll need to download Xcode to a Mac (can't upload from a PC). You'll create certificates online and download them. Create the app in Xcode, porting it over with PhoneGap, attach the certificates, and create the compiled file in Xcode. Create the app's detail page and upload the file. Wait a week for Apple to tell you whether your app has been approved or not.
My sig has details on these steps.