If a word comes up with the wobbly red line underneath then the computer says it is misspelled or incorrectly capitalized. If you right click on any word it will offer alternatives or correct spellings, obviously if it is a made up word like oojamaflip it cannot help (mine offered flameproof). If the word is underlined as mentioned before but is a name (Rik is underlined in the previous post) or an unusual word or postcode etc. that is not in the spell checker, you can add it by right clicking and then clicking on add to dictionary
You should find your spell checker in the "edit" menu ( the one with cut & paste in it ) normally right at the bottom.
"Check wile you type is an option in the "Settings" menu on inferiour machines or prefferences menu on good ones.