How to use the timer0 to clock the usi?(attiny84)

it is written in table 14-2, page number 128 . i want to ask- which compare match triggers it?
how to make it do it ? aaaaaaaa i am confused completely!!
i searched the datasheet of the attiny84 , but did not find anything.nor did i find anything on the internet.

table 14-2; page 128 in the datasheet*

please say something

Try it?

I believe it is Compare A.

how?(what values to set in which register)