arrowdog, welcome to the forum and the world of reloading.
Follow the reloading book guidelines for charge and oal. Load a few at the low end and then add a grain or two and load another 5-10 rds. Depending on how wide the "SAFE" range of loads given in the manual are, do it again. With a narrow load range .1 gr steps may be enough. Example: if the load range is from 3.9grs to 4.9grs, load some in ".2gr" steps. If the load range is 4.0grs to 4.5 grs, load in .1 gr steps.
Shoot these, starting with the lightest loads. Shoot each load on a different target. "Usually" somewhere in the middle range of your load data, the groups will start to tighten up and the powder will burn cleaner. This means your getting close to efficient combustion for that powder at that oal, that bullet in that pistol..
Now you can make small changes to the load --still within the published data--and see if it gets better groups or worse. Your tuning it to your needs. Always watch for signs of overpressure and shoot "slowly" to make sure you get BOTH a "BANG" and a "Hole in the target"---NO SQUIB.
Change any component (Pistol, Powder, Bullet or OAL) and you have to start again from the bottom of the published load data and work up slowly.
Hope this makes sense. Enjoy the process and stay SAFE, it's very satisfying to know "YOUR Load" shoots well in "Your Pistol".