You probably mean phonetic symbols (most schemes of phonemicizing
English use very few letters that aren't on a standard keyboard, since
they were invented by people with typewriters). You get at them with
the Insert Symbol button (capital omega), in the Unicode range called
IPA Extensions. (But you'll need theta, which they economically didn't
duplicate from the Greek range, and Edh, which is in Latin-1
Supplement, because they're ready for you to type Icelandic.)