letter of invitation in 30 minutes

i need a letter of invitation for someone who wants to come visit me in the USA 

this person will come spend her vocations in the U.S 

– she will come in August and she will stay for one month 

– she will pay her personal expenses but i will provide my apartment for her to stay 

– we will visit some tourists places in the U.S. ( Miami, Los Angeles,New York)