Remote Access to Time Capsule Configuration

Can you remotely access an airport extreme and change port forwarding

Yes you can

Can you supply to steps to set this up I'll be using my macbook pro to access the settings

You don't say which version of the AirPort Extreme you have but these instructions are reasonably generic:
How to set up port forwarding | Macworld

https://discussions.apple.com/docs/DOC-3413

OK I understand that will allow me access to files on the disk but will it also allow me to change configuration of the airport extreme such as reserving IP addresses and forwarding ports remotely.

Airport utility 7.6.4

Enable remote access on the extreme and then use airport utility and connect to via your external IP address