(Before I start I would like to say that I am a noob at coding but I am still learning html and php)

Ok so, is someone kind enough to code the following thing I'm gonna write that would be great :

So I want a simple text box in the middle of the page (with round corners if possible) and all the information that gets written in there is directly transfered to another private page ehich I only have access to. Please note that I don't really care about the fonts and all that stuff that I can add by myself.

If you need further information please say so !

Thank you for responding,