Unlocking your iCloud account
If you are typing the correct password, it is likely you need to use an "App Specific Passsword". This will be the case if you have 2-factor authentication or 2-step authentication turned on. App-specific passwords are a security measure designed to keep your Apple password safe so are a very secure way to connect to Speaking Email (full details here from Apple).
It is easy to create an app-specific password.
1. Sign in to your Apple ID account page.
2. If you have 2-factor authentication turned on you will see an "app specific passwords" section. Click on that link. (If you don't have it you can turn it on here)
3. Follow the instructions and type the generated password in the password field in Speaking Email.
Another possibility is your account may have been locked for security reasons by Apple. This is easy to unlock, just go to iCloud online and try to sign in there. If your account is locked you will be forwarded to iForgot and given instructions.