Cakephp 3 depends a lot on using composer, so youll need to get that first.; http://getcomposer.org/

Once youve set up composer you can create a brand new cakephp3 app by;

1. Going to your web servers “htdocs” folder. I.e if your using xammp it should be; C:xampphtdocs
2. Open a command windows here and type;

   composer create-project --prefer-dist cakephp/app my_app_name

3. Cakephp will create a folder in your htdocs folder called ” my_app_name”
4. Open http://localhost/my_app_name

Cakephp 3 installation:
http://book.cakephp.org/3.0/en/installation.html