After successfully unpacking the distribution you should proceed by processing the files fdprefix.drv, preload.drv, and fontdef.drv with LATEX.
Read them carefully; they explain the contents of the files fdprefix.tex, preload.tex, and fontdef.tex. Normally you can leave those files as they come from the distribution but in some circumstances (explained in the documentation) it may be better to modify some of them slightly. For example, preload.tex defines what fonts to preload into your format. The default there is to preload Computer Modern fonts suitable for documents with a default type size of 10pt. However, if most of your documents use the |11pt| option this default is not really appropriate.
If you are not sure if it is necessary to modify those files, leave them alone and proceed by making a new format file. The worst that can happen is that you later have to redo this process.