Sidebar posting???

I have tried posting the following twitter widget into my homepage sidebar:

<a href="https://twitter.com/nathanevansart">Tweets by @nathanevansart</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+"://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>

[Moderator Note: Please post code & markup between backticks or use the code button. Your posted code may now have been permanently damaged by the forum’s parser.]

I tried doing it by going to Appearance > Widgets > then add a text box to sidebar widgets.

I also tried doing it by going to Appearance > Editor

I really need to post things in my sidebar. Any help is much appreciated!