Tax filings for new MD.

Would like to ask how to file taxes as professional, whether it must be manually quarterly at your registered office or you could do it electronically? Glanced through their electronic filing page, it seems you need to be a large income individual to must enroll there with enrolled bank account for it...

On the other side, are there easy-to-understand sources out there to simplify understanding the basics on tax filings for MDs? I did ask the RDO I registered with through e-mails, their responses are still confusing for me.