If you want to do it manually,
Paste the cert, click the button, then POST the outputted JSON file to the log’s /ct/v1/add-chain endpoint using a command such as:
wget --post-file=<json_file> https://ct.googleapis.com/rocketeer/ct/v1/add-chain
Download wget here: http://gnuwin32.sourceforge.net/packages/wget.htm
There’s a list of logs at https://crt.sh/?a=1