1) Press the root key (refer the key map for all English to geez conversion), lets try "h" as an example
2) If that is the geez letter you were looking for then great! But if you want to modify it to the other sounds of the same root category, press any one of the modifier keys. Like in the example below.
3) And that is it , as a reminder the root can also be a combination of one english letter and/or shift or caps keys