Problems with Spanish characters

[Enrique Finot]

I have a website developed in Spanish with Dreamweaber CS4 and I have a database using my hosting server MySQL and phpMyAdmin facilities.
When I fill an user registration form from a browser and submit it, all the special Spanish language characters (ñ, á, é, é, í, ó, ú, ü, ¿, ¡, etc.) appears like this: Niño Agüero instead Niño Agüero, in phpMyAdmin MySQL database. When I edit and fix incorrect characters directly in the database, Spanish characters appear as a question mark in the browser.
I tried with 4 different browsers and I changed different MySQL collation alternatives as utf8_spanish_ci and latin1_spanish_ci, utf8_general_ci and the problem persists