how do i add the little line on top of a letter or n with a squiggle
example : informacion how do i add the little line on top of the O example: pequeno the little squiggle on top of the N
˜˜ you mean the tilde, there is two ways, on your keyboard there is the tilde at the left of number 1 below the F1 but very rare you can add that tilde on a top of a letter the most current way to do it is to use Alt and keep alt key in and then use 0241 ññññ keep the ALT Key in and then use your numeric pad and use 0241 Voila.
If you are using the forum, the letters with the tildes are at the bottom of the area where you are typing. Click on the letter you want.
This is in the technical support section on this site: http://www.spanishdict.com/answers/100808/how-to-type-spanish-letters-
There is also this method which they call the U.S. - International Keyboard: http://www.studyspanish.com/accents/typing.htm
The second method doesn't rearrange any letters on your keyboard.