Here begins your journey!

Hi everyone! As you already know, I've made a little riddle to celebrate my birthday, and the winner of this game will have as prize a full coloured piece from me :)
So let's go with the rules:

The thing is really simple, in each page, I'll propose a little question or puzzle related with my life. There will be clues in every page, so pay attention and be carefully.
Once you thing you got the solution, the way you'll pass to the next stage is simple:
Type the word, or words (separated with "_") as if they were the name of the html page.

The solution is "mandarina". To go to the next stage you must type in your browser:
Yes, you'll change "birthday.html" for "mandarina.html". No capital letters or special symbols apart from "_".

When you arrive to the last stage of the riddle, there will be a last key. To win the contest you'll have to send by note to my DA account that
key word before 23.59 of November the 8th. The first one sending the note will earn the piece. But don't give up, there will be prizes
for at least 2 runners up too...
So! Everything clear? Got it? Now you try!! :D