I wants to user input centre of wabpage

Answer 1

'align' attribute is deprecated

must use css styles instead:

<section id="mystyle">

#mystyle { text-align:center; }

Answer 2

surround the input tag with a section tag or something a tag of your choice and set its attribute to align="center"

eg.
<section align="center">
<input type="text"name="username"value="username"/>
</section>