Here are some general principles to use when teaching someone to read.
Each time you select a new letter(s), a new set of words will be presented. The goal is to get the learner to use their knowledge of letter sounds to blend them into recognizable words. Do not pronounce the words for the learner. Let them do all the hard work of figuring out how to pronounce a word. If they make a mistake, focus their attention on the letter where they made the mistake and get them to repeat the sound of that letter and then ask them to read the word again.
Decoding is the ability to sound out a word based on the reader's understanding of the sounds letters represent. Each new letter pattern gives a reader the ability to read many new words, sometimes hundreds of new words at a time. This is because even in English most words are written with regular spelling patterns.
At each stage the learner should repeat the words until they can read them at a natural speaking rate, or about 60 words per minute or 1 word per second. At this speed the brain has absorbed the letter to sound relationship and can work with it at the sub-conscious level. When the learner can read the current words at this speed they can move to the next lesson. You can randomize the order of the words on the page by checking the "sort randomly" checkbox.
When a child has read a word successfully, but you suspect that they don't know what it means, you should stop and talk about the word. Give a short easy definition and use it in a sample sentence. Vocabulary level 1 words are linked to a dictionary and can be accessed by clicking on the word. A popup appears with a definition and sample sentence for you to use. Clicking on the X or elsewhere on the page removes the popup. While learning one new letter can enable a child to read many new words, vocabulary must be learned one word at time.
Writing exercises can be easily made from the words you see on the screen by clicking on the Writing practise link. Print out the page and teach the learner to sound out each letter as they write it down. After a word is written completely the child should read the whole word before proceeding to the next one. This reinforces the letter-sound relationship in the mind of the learner.
Spelling is the reverse of reading and can be taught from the very beginning. At each stage a teacher or parent can use the words that have been presented in the current lesson to practice spelling. Read a word out loud to the learner and ask them to write it out.
It is easy to review previously learned letters and should be done regularly, especially if you notice that the learner is making mistakes on a letter. Simply unselect and then re-select the checkbox of the letter you wish to review. When you review previous letters you will usually get more vocabulary than when you first encountered the letter. This makes for good practise with new words.