I've searched how to do it a week, but haven't success and it's been a bottleneck in the work so, I decided to ask.
I put <h3><?php print t("strings translation"); ?></h3> in page.tpl.php and flush all caches and reload every languages available in the site.
And then I try to search for the string in /admin/config/regional/translate/i18n_string the options available are Fields, Node types, Menu, Taxonomy, Blocks.
But then I can't find the "strings translation" in /admin/config/regional/translate/translate.
I have read in drupal.org documentation but it seems like I'm missing something.
Could you please advice how to do it?
Are you missing echo in your code?
<h3><?php echo t("strings translation"); ?></h3>
I am not clear what are you looking for. But Stringoverrides modeule may solve your problem. It can translate any string across the project. But, if the string is inside t() function.