Use the existing breadcrumb plugin, its perfect for SnowFlat theme.
To centre the menu you have to apply some css in option of the plugin and it'll work as you want it to.
To center the menu in snowflat theme you can find css rule .qam-main-nav-wrapper in qa-styles.css and add text-align: center;
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.
May 7, 2020: Q2A 1.8.4 released!