Listen! How did they say that?
Here are some websites where you can hear various people speaking American English. It is a good idea to listen to someone speaking English at a normal pace every day.
http://www.manythings.org/videos/tom/ This website records sentences and give you time to repeat them.
http://www.antimoon.com/how/pronunc-soundsipa.htm This website lets you listen to all the English sounds, along with their symbols from the International Phonetic Alphabet (IPA).
http://ttsreader.com (This text-to-speech website allows you to write a sentence and then a recorded voice will speak what you have written. It's not quite the same as hearing a real person speak, but if you have questions about specific words, it is helpful.)
https://www.aprendemasingles.com/2016/02/24/ingles-basico-nuevo-texto-en-presente-simple-con-audio-y-vocabulario/ This website includes the text of the audio and is spoken a little more slowly than a normal pace.
These websites will give you an idea of some of the different American dialects; the speakers are from different areas of America.
