how to create specific appointments on specific days only (not a generic montly basis)

I'm trying to set up my appointments+ like this and I'm having trouble figuring how to do so:

I do events on specific sets of days (i.e. i have one on november 24, 25, 26)

In 2015 I will have events every weekend from January - July

My appointments are in 20 min increments

I have no service providers, just services

They have to prepay for their service.

How do i do this?

thanks!