To get onto FidoNet you need to have several different components:
A computer - almost any type of home computer will be fine.
A modem to connect your computer to other computers via a telephone line.
Some software for your computer.
A BBS phone number to call up with your modem
It is not generally possible to access FidoNet through the Internet, although there are exceptions (especially in the US). You can however send email to fidonet users through a gateway, of which there are several running on FidoNet.