Attiny25 to USB

Hello,
I have one Attiny25 and I want to use it's two I/O pins for USB Communications? How to do this? (In google I found V-USB but how to use it for Attiny25 ?)

thanks

I have found this: GitHub - rayshobby/hid-serial: HID-class serial communication for AVRs using V-USB, but It says that I have to burn modified bootloader but I'm using My arduino as programmer which is connected to Attiny25, how to do it? won't it burn bootloader to arduino or I don't have to use arduino as Programmer and I have to connect attiny25 directly to computer? and what is schematic for attiny25 (Library say's that it supports Attiny25)