Garage band question

Greetings,

It's Joseph here. I recently came across a page on apple's support website for garage band that states that you can load soundfonts, or other software instruments in to garage band for playing. My question is this: how is this done with Voice Over? I have a document on my hard drive detailing how a sighted person would do it, but I can find no way to do it with Voice Over. I am running OS X 10.10 and Garage Band 10.0.3. Many thanks for any and all assistance given!

Joseph