Once you have built the Wirego plugin for Wireshark (or downloaded a pre-built version), you should have a Wireshark plugin named wirego.so.
Refer to the Wireshark documentation to know where the plugin should be dropped. You may also want to take a look at https://www.wireshark.org/docs/wsug_html_chunked/ChConfigurationPluginFolders.html which may give different hints.
Another option is to start Wireshark, open the "About" dialog, click on the "Folders" tab and search for the "Personal Plugins" entry:
To make sure your plugin has been properly loaded, open Analyze>Enabled Protocols and search for "wirego".
If your golang plugin fails to load for any reason, the plugin will not appear on that list.
Once the Wirego plugin for Wireshark is installed open Wireshark preferences, select "Protocols" on the left menu and then locate "Wirego".
Click the "Browse" button to locate your plugin written in Go.
You will need to restart Wireshark for the changes to be applied.