"I have to open the shop."
Translation:Muszę otworzyć sklep.
Well, the situation is more complicated. For most people first thought will be "otworzyć", but your version is a possible interpretation. But it means that I have to open the show everyday, or every second Tuesday, anyway - regularly, generally. "otworzyć" is a one-time thing: open right now, open tomorrow, open next Thursday.
Anyway, added, as English would put it the same way.