I wish I am rich

When using wish, the tenses ‘go backwards’.

Current Wishes

Although the wish is for something now, use the past tense.

WrongRight
I wish I don’t have homework.I wish I didn’t have homework.
I wish she is my girlfriend.I wish she was my girlfriend.
I wish I can do magic.I wish I could do magic.

Past Wishes

Wishes in the past have to use the past perfect tense.
The past perfect tenses is had + done/eaten/gone etc.

WrongRight
I wish I studied harder when I was at school.I wish I had studied harder when I was at school.
She wishes she didn’t kiss him.She wishes she hadn’t kissed him.
He wishes he didn’t get drunk at the bar and acted stupidly in front of the staff.He wishes he hadn’t got drunk at the bar and acted stupidly in front of the staff.