I am from Spain, I have to make a trip to United States, and they recommended taking the ESTA VISA
anyone know or have experience <snip>
thanks for your answers.
[Edited: 2015 Jan 31 07:05 - traveltalesofawoollymammoth:258356 - No URL addresses please]
Unless you have extenuating circumstances (previously arrested, exposed to certain diseases, etc.) ESTA can normally be obtained from the US Customs Department website: https://esta.cbp.dhs.gov/esta/ If extenuating circumstances do apply, you'll almost certainly need to see a lawyer. Permission to visit can still be obtained, but it takes significant work.
The internet in Europe has a number of "US Visa Agencies" that are normally just wrappers around the official website. They take your information, pass it on to the Customs department, and then charge a fee for the privilege. Research these agencies in depth and be sure what service they are actually providing.
I don't know if same from Spain as UK, but I did ESTA online, it cost approx 14 US dollars and came through very quickly.