Entitlements of the employee upon resignation for salary delay

I am working in a reputed aluminium company for 5 years. For the last few years, the company is delaying salary so I decided to resign.

Now, what do I do to get my unpaid salaries and settlement?

Do I have to send a mail to the HR for the settlement?

And if they didn't take proper action, then only I have to go for legal action?

Please reply.