There are four ways to accomplish this,
The first, Take lots of money to your local software store and purchase a shiney, plastic shrink wrapped box full of Adobe stuff, inside you will find the program on a disk and a serial number, install, enjoy.
The second, pray for the serial number fairy to magically appear and write the required number on your forehead. Human sacrifice has proven unreliable in the past as a means to entice her arrival with said goodies.
The third, on certain Musical CD's, serial numbers are encrypted within the lyrics, Play the disk backwards listen carefully for any numbers spoken aloud in a foreign language. How do you get a CD player to go backwards? Just get a battery operated one and put the batteries in reverse polarity. Ignore the smoke coming from the inside of your player, they do that to scare people from trying to play their music backwards, a few flames aren't uncommon, but remember, you are trying to get something for free, and a little pain and suffering isn't so bad is it? Just remember to do this far away from any flamables, or better yet, go to a neighbor's house and use their basement.
The fourth,
Brute force attack, just keep entering in various serial numbers in until one works. I'll give you a hint, mine starts with the number one.
I used the playing the CD backwards method.
Not only do I now have a working copy of Photoshop CS2 but I now speak fluent Swahili, Russian and mandarin.
P.S. No-one on this site will help you get cracked software, if they do it will result in a ban, hence the lack of help for you here.
There are plenty of other forum that will help you go down that route if that is your desire.
If you want to use that program, then you either have to be creative enough to get it via a less than genuine source or have a spare £450 knocking around.