Prerequsites : 
1.      
Java 1.6 or above.
2.      
Apache Tomcat
Server 6.0 or above.
3.      
OpenDJ as a directory server.
4.      
OpenAm as an
identity provider.
 1.   
Steps to install Java 1.6 in Linux are here
 2.  Installing openDJ
    OpenDJ provides a user directory service
based upon LDAP standards, creating a simple, easy to deploy and  scalable option to use as a user data store.
You can download openDJ(Zip) setup here http://forgerock.com/opendj-downloads/ 
  
Installing OpenDJ
in windows:  Once you have downloaded
the openDJ unzip it,  open the folder and
click setup.bat and follow the steps below to install openDJ in windows
 Password: opendj
 Fully Qualified host name and Directory Data will be used
while configuring Directory server in openAM
Once the installation is done login into opendj with the
opendj as password. You can manage different users in the manage entries
section on the sidebar.
To open opendj again go to installation directory. In my
case it is C:\Users\NareshJella\OpenDJ-2.5.0-Xpress1\OpenDJ-2.5.0-Xpress1\bat
and double click  control-panel.bat .
3. Install Tomcat server6.0 or above and add the following
entries in the host file and save it        
 C:\Windows\System32\drivers\etc\hosts
    XXX.XXX.XXX.XXX  openam.example.com 
   127.0.0.1  website.example.com
    (where XXX.XXX.XXX.XXX
is the public ip address of the system in 
which tomcat is installed )   
Once this is done you should be able to see tomcat
running  at 
http://openam.example.com:80 (80 is the
port in which our Tomcat is running it may be different for you)  
 
Click on manager app and enter your username and password.
Now go to ‘WAR file to deploy’ section and choose the openAm
war file you downloaded and click on deploy. If everything goes well you should
be able to see an entry in the applications section
Note : If you get any error
related to ‘multipart-config‘ then go to      
 C:\Program Files\Apache Software
Foundation\Tomcat 7.0\webapps\manager\WEB-INF and open web.xml and
increase the max-file-size of the multi-part config tag to the size specified
in the error message
Click on openam application you will be directed to the
OpenAm configuration page as below
Password : cangetinam
   Directory name is
the fully qualified host name and Root Suffix is the Directory Data which you
gave during openDJ installation.
Password : cangetindj (password that is given during
installation of OpenDJ)
Password : cangetinpa
Login with the administrator credentials i.e
User name : amadmin
Password   :
cangetinam
Follow this link for further configurations like  
Creating Users
Creating a Web Agent
Creating an Access Policy
Configuring for
Single sign on
   
Follow the below link to configure SSO on openAm and Salesforce