Guitar bending technique?

Denis, if you've only been playing a "couple of months", you're getting ahead of yourself by working on solos and bends. Please don't take this wrong, but unless you're an amazing prodigy, you have skipped over a lot of basic knowledge and technique.

To specifically answer your question, striking one string without hitting others is a matter of control....and lots of practice. One trick is to "anchor" your strumming hand. There are several techniques for anchoring, and no one correct way. I lightly rest the heel of my hand on the bridge. When I say "rest", it's more like hovering and occasionally brushing against the bridge. Sometimes, I rest my pinky on the pick guard as a reference point. The point is to use something as a reference point so that you know where your hand is in relation to the strings.

Once you establish a reference point, the rest is practice, practice, practice. When you practice...and this applies to everything on guitar....start slowly and don't play any faster than you can go accurately. Practice is all about building muscle memory, and if you practice sloppy, that's what your muscles will remember.