What is needed for tourist visa-USA? which are the conditions?

The requirements and application for a B-2 tourist visa for the U.S. are exactly the same for everyone in the world. The BIGGEST requirement is that you be able to prove you have compelling reasons to return to your home country when your approved time in the U.S. is over. The embassy will presume you are going to violate your visa...they presume this of every person who applies. This is because so many people do violate the terms of their visa...it is extremely common. See site below and follow the instrutions there for the application process.

Q: Can a VWP applicant for Admission Be Readmitted To the United States Following a Short Trip To an Adjacent Island, Canada, or Mexico? A: Generally, VWP candidates admitted below the VWP could also be readmitted to the United States after a departure to Canada or Mexico or adjoining islands for the steadiness in their common admission interval furnished the individual: Can establish an legal interval of admission that has now not expired, Plans to leave the United States no later than the expiration date in their interval of admission, Presents legitimate, unexpired passports which replicate admission to the United States below the VWP, and Continues to fulfill all standards set forth in eight CFR 217 and segment 217 of the Immigration and Nationality Act (INA) 0020 aside from arrival on a signatory service.