A: Like it?
B: Sure
A: That means No

Seriously? "Sure" means No? Can you guide me to use it right?

By itself, sure can seem not very enthusiastic. Oftentimes putting an exclamation point "Sure!" or saying something like "yes!" or "yeah!" instead in that situation will make it clearer that you like it :)
But it doesn't mean outright no, unless said sarcastically....

Not quite. Sure has two different uses: 1. giving permission 2. Being sure. You need to use it as an adverb to make it "being sure" if someone is asking your opinion: "Like it?" "I sure do." That has a very different meaning than "sure" by itself. "Sure" by itself is used to give permission or say "ok i'll do it" if someone is asking you to do something. So when you just say "sure" after they ask you if you like it, you make it sound like they were just asking your permission to say "yes" and you're just complying even though you don't necessarily feel that way. It's because it's a permission word. When you use it like an adverb "I sure do" then the meanings of "being sure" stays intact.

I agree somewhat alphanumeric...
It can also be passive. For example, like a shrug.
"Do you like my poem?"
"Sure."

Will often have the hidden meaning of "it's only ok..."

HOWEVER, alphanumeric is correct. If someone asks you:
"Wanna go to a movie?"
"Sure." Would be a good response :)

Haha no problem at all! :)