How to tighten brakes just at the wheel?

Hi Nancy,

There are, of course, many different models of walkers available so it's hard to be specific about yours without knowing your make and model. It would help immensely if you could add some pictures of your handle grip and the brake mechanism to your question.

Adding images to an existing question - iFixit Repair Guide

Given that, I can give you some general information, as most of them operate on the same general principle; you have a wire that's pulled by the handle which squeezes a pair of rubber pads on the wheel to slow it down and stop it, very much the same way disk brakes work on cars.

WikiHow has a guide on how to adjust bicycle brakes that should give you a fair idea of what you need to do.

How to Adjust Bike Brakes: 11 Steps (with Pictures) - wikiHow

It has various methods; I'd suggest concentrating on Method 2, as it should be correct if there's no adjustment on the handle grip of yours.

So go ahead and see if that helps, and if you need more help add some photos and we'll help you figure out what you need to do.