Module configuration translation
In config there are only few field types that are translatable by default text, label and i think date_format(you can check the schema types to see which field types exactly are translatable by default). You can also make any value translatable by adding the translatable: true flag to the field. Now, copy your config/install directory into config/install/language/LANGCODE and edit each one of those config files and keep only the translatable fields..and translate those :)

If you want to provide translations for you module so t() function will pick them up, that is a bit strange in D8 compared to D7 but to put it simply you have to edit your module's info file and put in the following lines:

'interface translation project': yourprojectname
'interface translation server pattern': relativepathtotranslationsdirectory/%project-%version.%language.po