Translation:Where is the entrance?
Context. There are few if any situations in which one would be used where the other would be acceptable, so confusing the two would not be very easy. It is like the number 0 (zero) and the letter O. Letters are not often used in places you would expect numbers, and vice versa. Katakana is not often used in the same way as kanji.
Visually, the two are pretty much identical. In handwriting, the characters are written using the same strokes. In type and on computers, the two might have subtle variations to prevent mistaking one for the other, but there is no standard distinction. Different fonts will have different ways to represent it.
I would suggest using the 3 free levels of WaniKani! You learn this kanji and it gives you a mnemonic to help remember it. I made up my own that helps me:
You approach a door. It's really eerie (iri). A Kardashian is there. "Buy Gucci (guchi)," she says. It is the ENTRANCE to Hell.
But most of the kanji in this lesson, I believe, is covered in levels 1-3 of WaniKani. It is very helpful!
When asking where something is located, "doko" and "dochira" mean the same thing, "dochira" is just more polite. If you type in your own answer, you should be able to use either "doko" or "dochira".
Please read the link I posted (for those on mobile who can't click the link: https://learnjapanesedaily.com/japanese-grammar-%E3%81%A9%E3%81%93%EF%BC%8F%E3%81%A9%E3%81%A1%E3%82%89-doko-dochira.html). どこ and どちら are both used to mean "where".
As AndrewFlan10 stated, "Where is the entrance at" is incorrect in English.
"Where is the entrance?" is grammatically-correct English. The "at" is superfluous. In casual conversation, most English speakers would understand, but the unneccessary "at" in this sentence would be frowned upon in a more formal setting.