I’d strongly recommend you use a virtual machine for your capture - it’s nice to have a VM snapshot handy before you try to capture, because if there’s a problem in Sysprep you have to start over.
You’d need to install the OS and Bigfix client. Once you have it patched, configured, (and snapshotted), I’m pretty sure there’s a Capture dashboard (away from my console and can’t look now). The Wizard asks where to save the captured WIM file (a network share and credentials). When you complete the Wizard, it sends an action to the client. It copies a bootable WinPE image to the client, runs Sysprep on it, reboots into the WinPE, executes the capture, and copies the captured WIM to the share you specified.
Once that’s done, copy the WIM image and associated info files to your console machine, and upload it to Bigfix using the Image Library dashboard. Once uploaded, create a Bare Metal profile for it and ‘Send Profile’ to your bare metal server.
Then you can boot additional clients into PXE to download the image to them.