This letter should detail the purpose of their visit, the length of their stay, and how they will financially support themselves while they are here. Although not a requirement, your U.S. host can write a letter.We've provided a sample invitation letter for a B-2 visitor visa. Full Name and Contact Information – The letter should begin with the host's full name, address, and contact details. All letters of invitation will be sent via regular mail unless you provide a valid Federal Express or DHL account number. Describe the visit in detail. Include the invitee's full name, passport number, and date of birth. There is no requirement for an invitation letter. If you want to send on send it to your parents who in turn may present it to the US consulate. You must: 1) complete the online visa application and 2) print the application form confirmation page to bring to your interview.