MAX_CONNECTIONS ??

I need help to alter max_connections em my database, this parameter stay in defalt  MAX_CONNECTIONS=100
I want to change for MAX_CONNECTIONS=300.
about parameters below, need to change anything?

1 -sysctl.conf

kernel.shmmax = 68719476736
kernel.shmall = 4294967296
# - Memory -

2-Postgresql.conf
shared_buffers = 2048MB                                         
temp_buffers = 12MB                                                   
work_mem = 12MB                    
maintenance_work_mem = 128MB                         
max_fsm_pages =   4000000                              
max_fsm_relations = 5000           
                                 
Thanks for help