I want to start online teaching centre, will you help to know regarding......?

dear sir, madm, i am experienced lecturer, had experience in online teaching. thus i know little bit. but now i want to start online teaching centre. hence i want to know what kind of software be useful to teach unlimited number of students in a session. and what kind of tools are at present used for online teaching? i know some software tools but they are restricted only to limited candidates,, but i want to conduct and accomodate students in unlimited number of candidates at a session. do youknow any of such kind of software , technology, tools could be used for that....please help me to know,,, thank you