How you type umlauts depends on what kind of computer you are using: Mac, PC with number pad, or PC laptop without number pad. The two links below should give you all the information you need, but I will try to summarize for quick reference.

On a Mac, you simply hold the OPTION (or alt) key down while pressing the letter u. (You must HOLD the option key, not simply press it once.) Then release and press the letter you want the umlaut over (a, o or u). A total of two keystrokes: option-u, then a = ä. To type ß, hold option and press s.

On a PC, there are many different options which are harder to explain. See the links below for some tips, but you'll need to find which option works best for you personally.

On any PC, you can open the CHARACTER MAP application to find the letter you need. Search on Character Map in the Start Menu, and open the app -- it should be self-explanatory but you can view an explanatory video here.

On a PC with a number pad, some people find it easiest to type the 4-digit ALT CODES for each letter. Hold the ALT key while typing the four-digit code you need. See this link for the codes for each letter.

Another option which works well is to set your keyboard (in the Settings menu from the windows icon in the toolbar) to be "US International" layout. This does not change the standard typing on your keyboard, but you are now able to press the quotation mark before a letter in order to get an umlaut. Once you've changed your keyboard to "US International", simply press the quotation (") key, then release and type the letter you want under it: '"' + a = ä. To type ß, use the right alt key plus s = RightAlt + s = ß.

There are many guides online to help you figure out the best way to type umlauts and special characters. Here are two links for you to browse for help:
link 1: simple explanation of Mac and PC umlauts
link 2: more options explained for various situations

Finally, should you have any difficulty with the above methods, as a last resort you can simply copy and paste from any document, so I will include them here. The umlauted letters you may need at some point are:

ä ö ü Ä Ö Ü ß

When using many online textbooks for language learning, there is a character palette available on the textbook website. For example on McGraw-Hill Connect, the character palette is available whenever you're typing into a blank space, so you can simply select the special characters you need there. As an alternative to any of the above methods, you can also use THIS HELPFUL WEBSITE to type words you need, then simply copy and paste from there into your Word processing document or into the discussion board areas that you are typing into.