After launching STTM, by default you can search for a shabad by entering the first letter of each word. For example, if the shabad is ਗੁਰੁ ਮੇਰੈ ਸੰਗਿ ਸਦਾ ਹੈ ਨਾਲੇ , you would enter 
Alternatively, you can click on the gurmukhi keyboard icon and type in the letters manually.
gmsshn.Alternatively, you can click on the gurmukhi keyboard icon and type in the letters manually.