how to comment out a line in vim code example

Example: vim comment block

#for commenting:
Press ESC
:[StartNumber],[ENDNumber]s/^/#
:66,70s/^/#

for uncommenting:
Press ESC
:[StartNumber],[ENDNumber]s/^#/
:66,70s/^#/

#PS: To see line numbers:
Pres ESC
:set number