Well, it is clear that previously did not work with Bitrix.
Given that Bitrix works on components, then you need to first find out exactly which component is used on the page that you need.
For example, in the catalog, it will most likely be bitrix: catalog, but there are also custom recorders, you can find out which component by going to the index page of the section you need. For example, you need to register meta tags for products.
The path of each product is as follows: site.ru / catalog / product code / In this case, go to the catalog folder in the project and open index.php to see what components it contains. There may be several. In this example, we will need bitrix: catalog. Well, here how lucky. Either the developers did everything according to the rules and created a site template in the / local / templates / folder or NOT according to the rules in the / bitrix / templates / folder in any case, our template.php will be located along these paths (and see for yourself how it is implemented) :
1) If according to the rules the custom component / local / components / space_name_ to_ to which_component_component_name / component / name / template name / template / php is assigned
2) If according to the rules a custom component, but its template in the site template / local / templates / name_site_companying_name/components/space_space_name_to_to which_component_specific_name/template.php_name_php_
3) if the custom BUT NOT BY THE RULES, then the 2 upper cases, only instead of the local folder, will be a bitrix folder.
4) If a standard component according to the rules / local / templates / site_name_company/components/bitrix/_component_name / component_time_name/template.php
5) If a standard component, BUT NOT by the rules, then the 4th item, instead of local, will be bitrix
Here are the ways where your template.php can be stored.
You recognize which site template, through the admin panel, on index.php in the right directories, find out which component is needed and which template. eg
$ APPLICATION-> IncludeComponent ("samovar: user.profile", "profile" ..
This is a custom component, samovar is a space, user.profile is the name of the component, profile is a template. Therefore, according to the rules, the path to tempate.php will be as follows:
/local/components/samovar/user.profile/templates/profile/template.php
But your problem will not solve it! You do not even need template.php, but component_epilog.php
Because the components of Bitrix cache their templates and just your values will be cached for different products, the same tags will be) component_epilog.php is NOT cached.
In general, META tags can be set in the setting of the element in the admin panel in the SEO tab, and for pages through the front office through the control panel. In the component, set the checkbox in the parameters, "set keywords", "page description", etc. Similarly. Even if it is done through code, it is clearly not using
$ APPLICATION-> AddHeadString ('your_code', true)
And through $ APPLICATION-> SetPageProperty ('property code', 'string');
The title is set via $ APPLICATION-> SetTitle ('string');
Well, and this is not all. Bitrix is a fucking dark forest where you can do the same thing in the same way in the 500,500 ways.
If that component_epilog.php should be NEXT with template.php. If it is not there, then it needs to be created and the first thing to do in it is to add the Bitrix prologue.