Thank you for your question!
If you travel to Vietnam by air, we suggest that you should apply for Vietnam on arrival here since it is more convenient, faster and even cheaper. If it is not your case, you can obtain for your visa at the nearest Vietnam embassy where you are living. The required documents that you have to submit are a valid origin passport, an application form (available at the embassy), 1 passport-sized photo and Vietnam visa fee (in cash).
Hopefully, our information is clear and helpful for you.