How do I upgrade from Asterisk 1.8.20 to 13?

Asterisk Asterisk Support
#1

How do I go about upgrading from Asterisk 1.8.30 to 13?

#2

These documents might help you
https://wiki.asterisk.org/wiki/display/AST/Upgrading+to+Asterisk+13
https://wiki.asterisk.org/wiki/display/AST/Updating+or+Upgrading+Asterisk