Do we use 'were' or 'is' here?

[Dark Magician]

Hi, my teachers

I wrote this sentence

[Yankee]

Hi Mba

You have the right idea, there are different ways to use 'wish'.

Your sentence uses wish to give a greeting to people.

I wish you merry Christmas and happy New Year and Eid Mubarak.
I wish you peace this year. / I wish you a peaceful world.

When you wish for something to be true now which is not true, then you would formulate the sentence differently:
I wish the world were at peace.

Amy

[Sultano]

I wish you were here now. ( present )- He is not here for the time being.
I wish you had been here yesterday. ( past ) - He wasn't here yesterday.