After adding the bootloader, you can now upload via arduino. There's a testsketch in this repo if you just want to blink the debug LED. Write your sketch as usual. Connect your attiny to your USB ...

"%~dp0\hardware\tools\avr/bin/avrdude" -C"%~dp0\hardware\tools\avr/etc/avrdude.conf" -v -pattiny85 -cstk500v1 -PCOM7 -b19200 -Uflash:w:"%~dp0\t85_default.hex":i -U ...