Informed Webmaster

To give you some valid advice, we need some information.
- Did you use a CMS like Wordpress to create the website(we need to know if we need to recommend plug-ins for a specific CMS)?
- What back end are you using. E.g. is it php server side scripts you're looking for?
- Is the website using a database server like MySQL, Microsoft SQL Server etc.?

Picture publishing, review adding and search features will almost always require some kind of server processing(like php), and often some kind of database server(like MySQL).

If you don't know maybe you can post a non-live link to the website, so we can see for our self what you are using?

Looking at Squarespace's website, they don't support server side scripting or databases:

Squarespace doesn’t support server-side code, including PHP, Ruby, Ruby on Rails, and SQL

Source: https://support.squarespace.com/hc/en-u ... -your-site

So the functionality you asking for, would most likely not be usable with Squarespace. I see three options:
- See if Squarespace has some add-ons that you can use with the website
- Transfer your website to a normal hosting account somewhere that supports server side scripting like php and database(s) like MySQL
- Use javascript or an iframe to include functionality from a 3rd part website that supports server side scripting/databases

So i think you need plug-ins that is hosted on other websites. For example, Facebook has a commend plug-in that you could add to your website with javascript, since the commends users make would be send to Facebook being processed on their serve side and added to there database, so it can be displayed on your website via javascript. If you want something self hosted, then you will most likely need a new hosting account with support for server side scripting and database.