how i put an image at the top of this blogger blog

(this is how it looked before i removed it.) go to your control panel > Template > Edit HTML > then scroll down to where you see this:

<div id="header-wrapper">
<b:section class="header" id="header" maxwidgets="1" showaddelement="no">
<b:widget id="Header1" locked="true" title="nick humphrey blog (Header)" type="Header">
</b:widget>
</b:section></div>

(your title= will obviously be different than mine...)

and replace it with this:

<div id="header-wrapper">
<b:section class="header" id="header" maxwidgets="1" showaddelement="no">
<b:widget id="Header1" locked="true" title="nick humphrey blog (Header)" type="Header">
</b:widget>
</b:section></div>
<div id="header-wrapper" style="border-width: 0pt;">
<center><img src="http://google.com/intl/en_ALL/images/logo.gif" /></center>
</div>

using obviously your own code, not mine, and with your own img src