"I have to open the shop."

Translation: Muszę otworzyć sklep.

[DavidLindon]

muszę otwierac sklep is not accepted?

[Jellei]

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.

[Garry_S]

Can I use "odkryć" instead of "otworzyć"?

[Jellei]

No, that's Russian.

Oh wait, you can. If you actually mean that you want to discover a shop... ;) Or maybe 'uncover' it from under a gigantic blanket? False friends are always fun :D

[Garry_S]

Thanks! :)