Do I need to know the past historic and present subjunctive tenses to communicate properly in French?

I've been told the past historic is only used in classical writing so do I need to know it. I'd also appreciate if anyone could give me a brief explanation of what the following things are:

- present subjunctive
- past participle
- present participle
- imperative
- auxiliary

thanks!

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).