العين is articulated from the epiglottis pushing against the back of the throat.
It is one of the hardest letters for those who do not have this in their own language, but the truth is if you can swallow, you can say this letter.
While swallowing, the epiglottis moves back against the throat just as it needs to when you pronounce ع. In order to articulate this letter, first swallow and notice the movement of the epiglottis in the throat. You will feel something moving downwards or against the back of your throat.
Now swallow again and at the point you feel the epiglottis against your throat, hold it, open your mouth and make a sound from there. Viola! You will have your ع In sha Allah (…and now you just need to practice) :-).