I want to know the benefit of the visit, why I...

We would like to inform you that if the invitation was sent to you to visit America, then after this stage the matter will be required to review the American embassy and apply.
you can get a USA tourist visa which is called B-2 and do as follows:
Step 1:
Complete the Application Form for Non-Immigrant Visa (DS-160)
Step 2:
Pay the fees.
Step 3:
Schedule an appointment at the site of this US immigration service. There are three information to schedule your appointment:
1. Passport number
2. CGI reference number of your visa fee receipt.
3. The 10 digit bar code number from your DS-160 Form Confirmation page.
Step 4:
Visit the US Embassy at the date and time of your visa interview. You must bring a hard copy of the letter of appointment, the confirmation page of the DS-160 form, a personal photograph taken during the previous six months, the present passport and all the old passports. Orders that do not have all of these items will not be accepted.
You have to submit the following documents when you apply:
•Current evidence of income, tax payments, real estate ownership, or ownership of business or assets.
•The plan of the trip / or any other explanation of your planned trip.
•A letter from your employer explaining your position, salary, duration of employment, any authorized leave, and the purpose of work, if any, from your trip to the United States.
•The criminal record of any arrest or conviction anywhere, even if you have completed your sentence or been pardoned after.
•Certificate of salary for the last three months of the bank transfer the salary.
•Hotel booking
•Booking of airline tickets.
•Valid passport for not less than six months.