How can I download and use a free trial of Adobe Photoshop CS4?
Unfortunately, you can't download a trial version of Adobe Photoshop CS4 (11.0) because there isn't an online resource available for this purpose. Nowadays, the application has been replaced by Adobe Photoshop 13.0. You can download a trial version for this version from the Adobe Downloads page.
Note: If you want, you can still download Adobe Photoshop CS4, but you will need a license in order to activate it.
Hm, strange question...
click on the download button, create the Adobe's account, download the trial version, install it then open and use))
if you new to Photoshop, try using guides and manuals, though it is not simple and rather long