Not knowing rules is fine, it is a starter campaign, though please read the quickstart guide, it gets you through the basic mechanics.
On Roll20, I will put up the maps, and all the mobs, giving you individual control over your own characters. You roll with the /r mechanic (/r d20 rolls a D20, /r d57 +4 Rolls a D57 and adds four, as a random example.) and the /gr mechanic, (/gr d20 and so on, this rolls directly to the GM (me) so other players can't see it, for subterfuge reasons.) Other than that, all there is for you to do is edit your character sheets when they change, and alter your health during a fight, which is done by clicking on your character, and writing +1, or -5 or similar in the red bubble that appears above them.
You start out together.
Quickstarts are fine.
Enkas, are you able to join? Sorry, but I need to know more exactly than a may, as it is the last slot.