How an offline classroom can be converted to an online classroom?

I am looking for a computer software or an application that would enable me to conduct my maths coaching classes online. I may have to shift my base to another city in a year or two.

I don't want to abandon my well established academic career which is financially sound. I heard that I have to acquire a virtual white board and projector that are very expensive.

Is there any other alternative? How an offline classroom can be converted to an online classroom? In other words, how do you convert a face to face training center into a virtual training center?

Online teaching helps retired moms.

A few hours ago, a friend of mine called my mobile number. It has been several months after I heard her voice. She is a retired teacher.

She makes use of her free time by teaching online and earning a decent sum every month. Though she is basically a Chemistry teacher, she teaches mathematics online.

She has amazing energy. She learnt to use a couple of devices to teach online from her home PC. She has been encouraging me to take up online teaching. May be I can consider the option.

Incidentally, she is my blogging trainee.