RDSP account

Hello everyone, I git many good advices and would like to ask another one. I became aware that I can open RDSP account as I have DTC certificate. I was wondering how it works- can I open anywhere , is it better in bank or financial institution? May be someone has any recommendations where to open? Do I have to contribute every month? Do they pay back in time since the year I have certificate? Will I be able to withdraw money from that? Thank you for anyone who will have time to reply