Simple way to add a search to your blog on Blogger.

• Click -> Layout
• Click -> Add a Gadget
• Click -> HTML/Javascript
• Paste -> Code below

<form action="/search" id="searchthis" method="get" style="display: inline;">
  <input id="search-box" name="q" size="30" style="height: 30px;" type="text" />
  <input id="search-btn" type="submit" value="Search" />
</form>