Adjust brake tension / stopping power
With caliper brakes like yours that's not the case. With some cantilever brakes adjusting them so that they contact the rim later can increase the mechanical advantage (leverage), making the brakes more powerful if then adjusted properly. But that's a usually-minor effect on a type of brake you don't have.

For your bike the suggestions Blam made in comments are correct. Start by cleaning your rims and pads.That means sanding or filing the dirty surface of the pad off, and wiping the rim with a wet cloth. Don't do that the other way round! Damaging your rim is expensive to fix, but brake pads are cheap. Most people don't bother trying to clean pads at all, they're cheap enough that it's easier to buy a new set.

In your case you appear to have two-piece pads, where there's a metal holder that accepts a rubber insert. That makes it even easier. First, buy new inserts. There should be a little split pin that holds each insert in place, which you need to pull out using pliers. Then slide out the existing inserts and put the new ones in, with new pins. Then adjust your brakes.

There are several web pages describing that process in more detail, like this one