Hi there! Because the forum you originally posted in is for beginners trying to learn the basics of Photoshop, I moved your question to the Photoshop General Discussion forum, where you'll get more specialized help.
To help others help you, please read through this article and provide any additional relevant details.
To add relevant info as suggested by Kendall (thank you):
I'm using CS6, version 13.0 x64; it's a psd file. My computer has 16 GB with 483 GB free.
The problem is an old one, the prints are too dark.
In the past I've guestimated by doing overall lightening, but this is a sloppy imprecise method.
Before going further, update your Photoshop. There were many bug fixes in 13.0.1 and at least one more thing has been fixed by subsequent updates such as 13.0.4 and 13.1.2.
Generally speaking, you may want to learn all about color-management, calibrate and profile your equipment, and make sure you set and use color-management preferences and settings appropriate for your needs for your display and printer.
Most color matching problems are rooted in the fact that the display monitor is not set to display your colors accurately. There is equipment you can use, but a really rough, poor-person's way to get started (or for use in the interim) can be to print an image, then adjust your monitor to make it look as close as possible to your print. Then when you edit your images you'll be preparing them for proper printing. This may involve changing settings on the monitor itself or in the display driver. But I caution you that you many never get things consistent and right without getting your head around what good color-management is all about.
Unfortunately, because of the complexity of the realm, it's proven near impossible to teach color-management one post at a time on a forum, but there are some good references out there. One of our members here, Gary Ballard, has published some good "getting started" info.
In the Print Settings, you select Photoshop manages colors and select your printer/paper type. The use the PrintSettings box to the left to select paper type again.
All these replies help. Some I'd done before and have also dusted off my x-rite i1 Display Pro to finally use.
HOWEVER, this website
shows the step by step calibration on the mac and if these windows are the way the apples are supposed to look then i've been doing in wrong for years!
(Fig. 3 Steps 1 & 2)
Only my white apple (step 3) looks right. The rest were wrong, so it's operator error.
Already the first test rpint looks much closer!
I will read the gballard.net tomorrow.
THANK YOU very much.