I have never hunted before, my goal isn't really hunting for hunting sake, I just wanna shoot up all these chipmunks that are wreaking havoc in my garden and eating my veggies.

My firearms experience is very limited.

Basically, I know how the sights work, I played Call of Duty and such, you line them up, so the front is in the middle of the gap of the rear sight. My problem is that I can only line them up if I only have one eye open. If i have both eyes open, I see both sights at the same time from a three-quarters perspective. This brings up problem #1, its hard for me to close just one eye. I guess I am not used to doing that with my eyelid. Most of the time I have to use my hand to close it, which is awkward when shooting a rifle. I tried using a glasses with one eye blacked out, but its still feels uncomfortable and awkward. Then there is problem #2. When I use one eye, my vision become much worse. I am only 31 yrs old, have no problem with sight in my everyday life what so ever. I put up a practice target about 60 feet or so. That's about the closest I can get to a chipmunk without worrying about him being scared and running away. The target is about the size of a plate. With 2 eyes, I can see everything perfectly, but with one eye I cant even see the lines marking the different rings and where the center is marked and the target itself become a little blurry. Problem is I cant line up the sights with 2 eyes open.

So anyway, what am i doing wrong? I know I seen people aim rifles with 2 eyes open on tv before, was that just for movies, or can you do this in real life. I am pretty sure its not my sight, but just something I am doing wrong, since i have no problem with my sight in everyday life.