Need a root canal but have a temporary filling ?

Okay so today i went to the dentist fot a filling but turned out mh cavity was too deep so i need a filling. So they were already drilling and all they do and ot started hirting so i let them know and thats when they told me i need a root canal. So they put some type of filling mixed with medice or something like that. They told me not to try and eat hard stuff on that side so i havent but i was wondering if i could brush that teeth or will it come off because i touched it with my finger and it got on it and yes it is dry by now it been 2 hours. And also do root canals hurt ? Sort of worried