Generally if you want to use some program, your best bet is to find a Linux program that does the same thing. For example there are a lot of image manipulation programs (Gimp etc.) that are as good as Photoshop, depending on what you want to do. Some Linux programs suck, some are as good as their Windows equivalents, and some are better.

If you absolutely need to run a Windows-only program, you have a couple choices:

1. Use WINE, which is sort of a Windows emulator. Pros, it works sometimes. Cons, it can be very hard to set up and get working, and it only works for certain programs.

2. Use VMware or another virtualization program, (which lets you run Windows in its entirety while still in Linux). Pros, it works extremely well and will run almost any Windows program. Cons, it's not free (though there are free versions) and it can be hard to set up too.

3. Dual boot. Pros, it's guaranteed to work. Cons, you have to reboot your computer every time you want to use a Windows program, which sucks, and communicating / transferring files between OSes can suck at times.