Strange, there is no entry for stýskat on neither English nor Czech Wiktionary... Is it a commonly used verb at all? There seems to be another verb postrádat which also means to miss. Then there is also chybět which we learnt in previous lessons... Which one of those is better to use in real life and is there any difference in them at all?
"Chybět" is the most general of them and the most used of them as well
"Stýskat se po" is reserved for people, things or activities we really love
"Postrádat" sounds formal, almost indifferent. It is appropriate when speaking about lack / shortage of something.