Read the theory and do the exercises that follow!
https://www.ego4u.com/en/cram-up/tests/present-progressive-1
https://www.perfect-english-grammar.com/present-continuous-exercise-1.html
https://agendaweb.org/verbs/present_continuous-exercises.html
https://www.englisch-hilfen.de/en/exercises/tenses/present_progressive_mix.htm
http://www.eclecticenglish.com/grammar/PresentContinuous1F.html
http://www.really-learn-english.com/present-progressive-exercises.html