The Penn State University has a glossary of commonly used keyboard symbols for accented letters, foreign characters, currency, math symbols and punctuations. Alt codes for instant messaging, drawing, arrows and trademark symbols are listed on Useful Shortcuts.
To enter the special character, ensure that the cursor is at the position where the character should be typed. Turn on the numeric key lock, the Num Lock key at the upper part of the keyboard. While pressing down the Alt key, type the number code using the numeric key pad. Using the numbers on the keyboard will not result to the corresponding character. If you are using a laptop or a keyboard without a numeric keypad, you may just have to copy and paste the character from a character map.