I would like to work for Mars. How can I get a chance to start my career in Mars? Please advise.

There are multiple routes in but as a starting point I'd always check the website for the latest opportunities (careers.mars.com). The 2 main routes are applying directly to a specific role or applying for a graduate program which typically takes graduates who have just finished university and gives them experience in different parts of the business. For data analysis / analytics roles these will typically require some form of experience working with data analysis technologies (e.g. Azure/AWS Platforms, Python/SQL/R languages), however the specifics will be posted on the role descriptions.