Anyone is more than welcome to jump in here and help me out if I'm giving bad info.
Look in your owners manual and it should have instructions regarding how to make this windage correction.
IF my memory serves, (I'm an old fart, so it's questionable ) you place the firearm in a vice(wrapped in a protective cloth from the "teeth"of the vice), and using a mallet and I assume a BRASS pin you gently tap the rear sight IN THE DIRECTION you wish to move the impact of the fired round.
Before you start hammering away, please refer to your owners manual, and I'll bet before long someone else will come along either confirming what I'm saying, or telling me I'm full of bs..
IF I had a quality firearm that needed such correction I would take it to a reputable gunsmith (not Bubba at the pawn shop) and have it done professionally. The price should be reasonable, and you won't scratch up your firearm. If the firearm is a SNS, hammer away.
And really "sometimes" the low selling price of a pistol doesn't really even make it a "Saturday night special".
For example, I don't consider the "HiPoint" pistols as SNS's altho they are extremely low priced. I don't own one, don't want to own one, and probably never will own one, but for folks with very limited budgets I believe they could certainly do worse than buying a HiPoint.
My understanding is that HiPoint has a lifetime warranty, no matter if you are the first or 23rd owner. From what I read, even tho they are uglier than Hilliary Clinton they generally work quite well. You wouldn't want to shoot 10,000 rounds out of one without expecting it to wear out, but hey, for the money you get a substantial, tho ugly, self defense weapon.
I DO have a HiPoint 9mm 995 Carbine. I only paid $150 for it several years ago and it has been an amazing little carbine. I put a $25 "red dot" scope on it and it feeds, shoots and is very accurate. It too came with a lifetime warranty, and I think it is a tremendous bargain. It's ugly.
My favorite caliber in a pistol is 9mm, and I wanted a 9mm companion rifle (carbine) and the HiPoint 995 beat out a Ruger that cost twice as much in a head to head shootout. That's why I bought one, and I recommend the little sucker to anyone who might have the same need.
As long as you are asking questions about Walthers don't be concerned about any SNS problems. I consider Walther, H&K, Sig as some of the finest centerfire pistols made.
I am confused at a few of the rimfire offerings of Walther and Sig tho, as the Walther P22 is definitely below average Walther standards, as is the Sig "Trailside" to Sigs normal standards.. All personal opinion of course.