If FreeBSD ports fail to build on DragonFly they don't get included in the dports repo. There may already be logs [here](http://muscles.dragonflybsd.org).

1. Begin with downloading the FreeBSD ports tree. See instructions [here](http://www.freebsd.org/ports/installing.html). Git repos are available [here](https://github.com/freebsd/).

2. Copy the broken port from your fresh FreeBSD ports tree into your dports tree. Now you can try building it on DragonFly and fix what's broken.

3. Submit a fix to FreeBSD ports or dports, depending on what the fix is. Ask on the lists or in the IRC channel if you don't know the appropriate place. dports issues are reported to [the dports issue tracker](https://github.com/jrmarino/DPorts/issues) and ports issues go to [FreeBSD's send-pr](http://www.freebsd.org/send-pr.html).

Other interesting links is the [dports main repo](https://github.com/jrmarino/DPorts) and [FreshPorts](http://www.freshports.org/), where you can search for ports.