Love the Metafontbook myself; and you likely won't be able to get very far with Metafont without reading it, as unlike the TeXbook, very few broad tutorials have been written about Metafont. Still, if you're only trying for one character, you can probably get away with it.
First, you need to put Metafont into font-making mode, rather than proof-making mode, so that it will produce a tfm file letting TeX know the dimensions of the character. Metafont will take any possible excuse to go back to proof-making mode; so I find the best way to do this is on the command line:
mf "\mode=localfont; input myfont.mf"
This will give you a tfm file (which TeX needs to set the character properly) and a gf file. Most drivers these days use compressed pk fonts rather than generic font files (gf), so you'll need to convert your gf; fortunately, this is a simple matter:
gftopk myfont.???gf myfont.pk
Now you've got
myfont.pk; now TeX can use your font. The most direct way to do this is the old-school plain TeX way:
This creates a font-changing command
\myfont; so when you're ready to use your character, issue that command followed by whatever character you used for your glyph. Say the character you've created is in position "a" of your font:
will put your character into your document. It's probably easier to write a macro to do this, so you don't have to worry about switching back to your default font every time you use the character:
You need the extra pair of braces on the second line or you'll permanently change the font to
myfont, which only has one character in it, so you'll get a whole lot of nothing in your output.
This process will let you use your font as long as the font is in the same directory as your document; if you need to use it elsewhere, you can either copy the files, or install it the way you'd install another font in your texmf-local tree.
Hope that helps. Happy Metafonting!