Do I need a lawyer to open a succession and about how much do it cost.Also do I need to file ths in the courthouse

I assume "to open a succession" is equivalent to a proceeding to probate a will or to be appointed personal representative of an intestate decedent. But since you use that peculiar language, I'm guessing you are not in the US. Where are you?

Any question on law needs to include your general locale as laws vary by area. Also terms vary by area and "open a succession" is not a term I'm familiar with. So can you be more detailed.