You didn't -- you crossed into the light, you just bought a dark pistol.
The first thing you need to convert is some dollars into smoke and noise. Shoot your pistol a while before you start making changes (except night sights). Learn to shoot "from the reset". Ask someone local to...
Trijicon and Meprolight both make good night sights.
I prefer Warren Tactical.
You will need a special tool to replace the rear sight. I'd recommend taking the pistol and your chosen sights to someone with the tool and the know-how, and pay him a few bucks to change out the sights.
I had a Mosquito and a P22; needless to say I only have a Mosquito now. ;)
An 11-year-old can probably handle either of those. Get her the one she likes better, and don't worry about re-training later on a different pistol with different controls.
I'm not suggesting that you don't understand this; perhaps you tripped over your keyboard a little.
2-1/2 to 3 inches at 25 yds is 10-12 MOA. The number of clicks you'll need to move the point of impact to the X depends on your sights. IF you have 1/2-MOA-per-click sights, that's 20-24 clicks...