It's not hard to learn how to build a prefabricated steel garage. However, it's not a walk in the park, and beginners might need an assistant to help out with building a metal garage. What makes it easy is that prefabricated sheds or prefabricated garages can be purchased as a DIY kit. It comes with a full frame system and self-drilling screws, sheet metal and trim, door frames, bolts, etc.
Even the big industrial steel building companies like 3CB and Olympia deliver DIY kits for small home garages or metal barns. Some companies like Garador will provide just about any and all parts needed for prefabricated sheds. Note that some companies like Versatube offer a selection of prefabricated garages that they will deliver as a kit. The sectional doors and windows are not usually included in the kit, and can be ordered separately or bought from a door company.
The location for the prefabricated garage has to be chosen carefully. It should be easily accessible from the place where the kit is being assembled nearby. There should be access available from all sides to put it together. Other factors to be considered include natural light, surrounding foliage, possible flooding and use or availability of electrical power inside the prefabricated shed once it is built.
There are online services and downloadable software with which people can fully design and customise a garage building before actually doing it for real. Programs like CAD Quest and Google Sketchup can be used to put together a full plan for the garage including floor plans, size, window and door placement, etc. Seeing a 3D model on-screen and making adjustments online before doing it for real helps to avoid mistakes that can be hard to correct once the prefabricated garage has been put together.
Once everything is planned out, that is, the kit has been delivered and everything is ready for assembly, start with the base rails. With the base rails in place, start assembling the wall and roof frames. Then attach the purlins and girts, and lastly the frames for the doors and windows. With the framework in place, the next step is to start with the sheet metal and put up the panels, trim, doors and roofing. Start with the side panels, and then move to the roof. The trim comes next, and then the doors.