Yeah there is a good bit of stuff to be deactivated before I find MSW to be bearable.
To change the auto-correct feature go to Tools on the menu bar, left click and then select AutoCorrect Options... from the menu that appears. The cursor will be flashing in the field "Replace:" for you to enter the keystrokes you want to use. Then hit the tab key or click on the field labelled "With:" to enter the full text that you want to be associated with your shorthand.
If you have already typed something out and copied it to your clipboard before going to the menu as above, then the second field will already contain that word as a default. This can be helpful when you are using autocorrect to do formatting stuff like subscript or superscript. For example if I want the computer to always give H2O a subscript 2, then I go to the trouble of doing it myself once, then selecting the word, and then entering plain old H2O into the first field. Note that the radio button for "formatted text" must be selected rather than the "plain text" button for this feature to work. I think it will default to that if you've copied formatted text but sometimes you have to do it manually.
If you want to make it stop autocorrecting a word, such as teh, you enter teh and then just click on the button marked "delete." Then it will no longer correct teh and you can wax poetic about your favorite teas.
