Hi Ramit, 

Odoo itself actually has a quite good documentation / tutorial about how to create your own themes. Have a look at https://www.odoo.com/documentation/10.0/howtos/themes.html

Regards, 

Yenthe 

Hi,

For creating a theme you can have a look at the available docs and the theme module available in the odoo app store,

Docs:

http://odoo-master.readthedocs.io/en/8.0/howtos/themes.html

https://www.odoo.com/documentation/10.0/howtos/themes.html

Theme Modules in App store : 

https://www.odoo.com/apps/themes?price=Free

Check the docs and the above modules and create your own theme.

Thanks