use this form:
<FORM name="form1" method="GET" action="check.php">
<input type="text" name="username" size="27" maxlength="32"></td>
<input type="reset" value="clear" name="B1">
<input type="submit" value="submit"></td>
</form>
and u'll get this result:
check.php?username=testing
Every element of the form is appended to the action usin the ? or & as a key=value pair when u submit it via GET. When usin POST, the data is not transmitted as a part of the URL but via HTTP-Header.