Custom image upload in backoffice and using with web api

[yisusalan]

I'm building a store completely independent from prestashop frontstore and communicating it to prestashop's backend via it's web apis but basically I want to know how I can upload some static pictures like a logo or background image in the backoffice and calling in it to my frontend from the web api.

I haven't really found a place to upload images from the backoffice except images from products or images that come from modules (which I can't really access through the web api).

 

Any help appreciated and I'm sorry if it's a dumb question but I've been roaming through all internet and documentations and can't really find anything about it.