Where to put css code to have a nontext widget centered?

See:

https://www.w3.org/Style/Examples/007/center.en.html

Generally, best to add CSS to a custom CSS option or plugin so it’s not lost when your theme or the plugin is updated.

But I dont see how I can label the item in order to have css affect it.

Here is the source code for the item when it is displaying on the front end:

<aside id="taxonomy_dropdown_widget-2" class="widget widget_taxonomy_dropdown_widget"><select name="taxonomy_dropdown_widget_dropdown_2" class="taxonomy_dropdown_widget_dropdown" onchange="document.location.href=this.options[this.selectedIndex].value;" id="taxonomy_dropdown_widget_dropdown_2"><option value="">Select Tag</option><option value="https://xxx.com/tag/jimmy-choo/">jimmy choo (1)</option><option value="https://xxx.com/tag/midi/">midi (1)</option><option value="https://xxx.com/tag/stripes/">stripes (1)</option></select></aside><aside id="text-14" class="widget widget_text">

There’s really no way to help with CSS without seeing the site.

Please also always use the code buttons when posting code –

https://codex.www.ads-software.com/Forum_Welcome#Posting_Code

Sorry, I thought I did. Here is the site:
https://alamodesty.opsecconsulting.com/

I am trying to to the tag drop down list on the right hand side about halfway through

You can use the ID or Class from the widget to add CSS – see this”

<aside id="taxonomy_dropdown_widget-2" class="widget widget_taxonomy_dropdown_widget">

Use the ID here:

#taxonomy_dropdown_widget-2 {
   text-align: center;
}

Since you are using a custom version of twentytwelve, add to the bottom of the style.css file.

Thank you