If you are just starting theory for the first time, it helps to know how to read notes on a staff (those are the lines that music is written on). You can start by using an app called TENUTO.

You can set the parameters of your note naming and even do timed tests. 

Another great app is Sight Singing. This will help improve your sight-reading. You have the option to use Solfege syllables or one vowel. It has a range of difficulty, time signatures and keys. 

Both apps can be downloaded from the App Store.

If you wish you start your Rudimentary to Harmony IV theory, e-mail and book in a time.