On the link you provide, instead of a textfield entry in the form (which is one single line) this is a text area (multiple lines), which is resizable.
The thing is that with a text area, the enter key acts a line break, where in q2a it is supposed to submit the form.
So you might change the text field to a text area input, but then you also need to add some sort of submission mean since the enter key won't do that anymore.
Typically, you need to add a button.
A "quick and dirty" (i.e. just thrown away, not quite tested) hack to test this:
In the qa-widget-ask-box.php (in qa-include folder) find, line 93:
<TD CLASS="qa-form-tall-data" STYLE="padding:8px;" WIDTH="*">
<INPUT NAME="title" TYPE="text" CLASS="qa-form-tall-text" STYLE="width:95%;">
</TD>
and replace with:
<TD CLASS="qa-form-tall-data" STYLE="padding:8px;" WIDTH="90%">
<TEXTAREA name="title" rows=1 cols=115></TEXTAREA>
</TD>
<TD CLASS="qa-form-tall-data" STYLE="padding:8px;" WIDTH="*">
<INPUT id="qa-login" type="submit" name="AskQuestion" value="Ask">
</TD>
This should roughly do the trick.
Bear in mind though that having the area resizable may end up with unexpected behaviour, and breakout the layout on client side since the whole thing hasn't been design with that in mind from ground up.
This may not also look very nice... you would probably have to dig a bit in the css to fine tune the appearence... however, you mention you are not a programmer (which I am not myself BTW)