If you are looking for a guide to help you translate OPMember strings using POedit, please follow the below instructions:
1. Download the POedit app here: https://poedit.net/download
Here's a Poedit guide: https://make.wordpress.org/polyglots/handbook/tools/poedit/
Close the app when done.
2. Go to /optimizemember/includes/translations via FTP or File Manager of your Cpanel
3. Open up Poedit and localize / translate the .poT file.
4. Hit Save when you’re done. A .mo file will be generated.
5. Rename the s2member.mo file to s2member-LOCALE.mo e.g. s2member-es_ES.mo for the Spanish in Spain. You can find your locale in the below link:
6. Upload the new .mo file to your wordpress site in /wp-content/plugins/.
7. Refresh browser when done.