How to operate windows apps on linux?
For example. Adobe photoshop, quark xpress, indesign, adobe illustrator?
SOME Windows Programs will work on Linux BUT NOT ALL!
The basic Linux Program is WINE (Which strangely stands for Wine is not an emulator). There are other programs which are based on WINE like PlayOnLinux http://www.playonlinux.com/en/ and Commercial Apps (which you need to pay for) like CrossOver http://www.codeweavers.com/
Many people use native Linux alternative instead - or Web based applications.
For Wine start looking here: http://appdb.winehq.org/
You will see that Adobe Photoshop CS3 and CS2 are on the "Silver List"
On PlayOnLinux Adobe Photoshop CS4 might work
A useful site is alternativeto.net
It shows e.g. that Linux alternatives to Adobe Photoshop are Gimp and Pinta. Web based alternatives are Pixlr Editor and Sumo.fm.