YOU SAID:

Ive decided to create a party

INTO JAPANESE

私はパーティーを作ることを決めた

BACK INTO ENGLISH

I decided to make a party

INTO JAPANESE

私はパーティーをすることにした

BACK INTO ENGLISH

I decided to have a party.

INTO JAPANESE

私はパーティーを持つことに決めました。

BACK INTO ENGLISH

I have decided to have a party.

INTO JAPANESE

私はパーティーを持つことに決めました。

BACK INTO ENGLISH

I have decided to have a party.