Buenos Días,
I am going to (Indiana) on (October) (23rd) because I have to work there.
1) Always capitalize months: January. February, March...
2) Also the names of cities.
Ismael, I want to give you a couple of pointers: 1) In English all proper nouns are capitalized. This includes the name of states.2) Also, there is no need for a comma.
Good luck!
I am going to Indiana* on October* 23rd because I have to wrok there.