I read few ways to do that but didn't worked out. I don't know why. Any suggestions?? If yes, can you please tell me steps to follow.
Add a custom logo
Customize the login page logo.
Prerequisites
Ensure that the maximum image height is 100px. If the logo image height exceeds this limit, the image is resized to 100px.
Review the loginCustomLogo setting details in the web.conf spec file.
Steps
1. (Optional) If you are using an image file, put it into the following directory location.
$SPLUNK_HOME/etc/apps//appserver/static/logo
2. Check the $SPLUNK_HOME/etc/system/local/ directory for a web.conf file. Use one of the following options.
File already exists in the directory
Locate the [settings] stanza in the file.
File does not exist in the directory
1. Create a new file called web.conf in the directory.
2. Add a [settings] stanza in the file.
https://docs.splunk.com/Documentation/Splunk/6.5.0/AdvancedDev/CustomizeLogin