How to Solder: Castellated Mounting Holes
Contributors:
Shawn Hymel
Shawn Hymel 
Resources and Going Further
Advanced Techniques
While it was originally created for PTH soldering, Joel shows some great advanced soldering techniques in this video.
If you have a small enough module or the right tip for the hot-air rework station, you can use the part-removal techniques shown by David in this video to desolder the module.
Resources
If you are interested in more information about soldering, here are some resources:
If you wish to design your own PCBs, we have an excellent series of tutorials covering the design process using Eagle, a free PCB design software.
How to Install and Setup EAGLE
Not just how to download and install EAGLE, but how to install the SparkFun EAGLE Libraries and scripts.
Using EAGLE: Schematic
How to design a PCB in EAGLE using through-hole parts.
Using EAGLE: Board Layout
Part 2 of the Using Eagle tutorials, this one covers how to lay out a board after designing a schematic.