How do I make an ad-hoc network (share internet via wifi)?

In network-manager there is a feature called "Create New Wireless Network".

There is no clear way to configure an ad-hoc network to use NAT to create a subnetwork for people connecting to this network, or to set that addresses should be sent from DHCP server on same network as the computer creating this wireless network.

Bridging or NATing needs to be made simple enough for average users to understand. If someone can explain to me how these are done graphically, I would appreciate it.

My instruction up to now:
1) sudo apt-get install dnsmasq-base
2) Using NetworkManager applet, create a new wireless network
3) [configure sending ip address via NAT/Bridge]...*unknown step*

Step 3 is where I need help. Thanks.