Yeah, Holly, as Blether said, there are plenty of ways to resize your photos within Photoshop, you don't need another program. After you've done all your tweaking to the shot, I'd save an un-compressed version of it, either as a photoshop file or maybe a tiff, in case you want to do something with it for print. yes, this eats up a lot of disc space. Get over it. Big hard drives are cheap these days, get a large one, or two, or a RAID set to mirror (RAID level 1.)
Then, if you're posting to the web, go to the Image menu, choose Image Size, and change it to the size you desire: 72 dpi for the web, then whatever actual dimensions you want in pixels or inches or whatever dimension you want. Be sure to check the Resample box, along with the Constrain Proportions box.
it's been resampled, you may
want to do some sharpening... or not...
Then, if you choose "File>>Save for Web & Devices" you'll get a dialog that allows you to choose the image type and tweak the amount of compression you want, giving you a before and after pane that shows the consequences of your choices, both visually and as a file size.
Also - regarding your white-balance issues - you'll have LOTS more control if you shoot RAW, and then upon opening the RAW file, use that dialog to adjust the color temperature until the whites are white. That gives you much more to tweak than the post-processing adjustments of levels, or curves, or color balance, or hue and saturation. The auto button often gets close, but you'll still usually want to tweak the blue-yellow (temperature) slider a bit, and then, you almost always need to adjust the exposure setting, and/or the black levels.
Of course it's even better to have the white balance set right in the camera, but the real-world lighting conditions don't always play along. You should try to avoid having different light sources with different color temperatures hitting your subject at the same time. If your plate is being lit by an incandescent lamp, but you're also sitting near the window, and it's simultaneously being lit by sunlight, you'll end up with parts of the shot too yellow or too blue, and there's no easy fix for that...
Edited by philadining, 13 October 2010 - 11:18 PM.