There are some things we need to write Bengali in photoshop CS3 CS5 CS6 Illustrator Dreamweaver Coreldraw.
Bangala ANSI font and Avro Keyboard.
You can download Bangala Font from https://www.omicronlab.com/bangla-fonts.html or direct download link https://www.omicronlab.com/download/fonts/kalpurush.ttf
You can download Avro Keyboard from http://www.omicronlab.com/avro-keyboard.html or direct download link http://www.omicronlab.com/download/setup_avrokeyboard_5.1.0.exe
Step 1 : Install Bangala ANSI Font
You can refer How to install fonts in Windows to install fonts. Or simply you can copy the font ttf file in to “Windows\fonts” folder.
Step 2 : Configure Avro keyboard software
Open Avro keyboard software. Then go to Avro Settings(in the menu)->Output as ANSI->Use ANSI anyway
Step 3 : Write in Photoshop CS3
Open Photoshop CS3
Choose Type Tool from the Tools window.
choose the Bangala font in the fonts list as shown in the figure.
Now you can write in Bengali in Photoshop CS3 or CS5 or CS6 or Illustrator or Dreamweaver or Coreldraw.