Should be a section on phonetics and spelling
learning the spelling of certain sounds and letters by trial and error just isn't a good system, and makes learning pronunciation more difficult then it should be.
You just started with Irish. It takes a little while to get familiar with the spelling and pronunciation. The best thing is to practice at least a couple of lessons every day. If you leave too much time in between, you not only forget the vocabulary, but also the sounds and the spelling, and you make it more difficult for yourself.
For spelling, it helps to write out the words by hand a couple of times, first, simply copying them and then writing them from memory.
Also, don’t progress to the next skill until you have practiced everything thoroughly and done at least to two or three levels of one specific skill to give your brain the opportunity to grasp spelling and pronunciation as well as the grammar.