MyBB Community Forums

I had a mybb forum remotely installed for me by another person. It uses 1.8.6 version.

Since the forum was remotely installed, how can I upload images? I want to change the theme, but only colors and styles work since I cannot upload images as far as I know.

also I keep seeing these pictures of a file viewer in the Admin control panel.. How do I find that? I can't find a file viewer.
Sorry for sounding noobish. I kinda am a noob.

Do I have to tell the person who installed my forum to install the images for me?

You have to ask the person for your ftp information. Well, as a site owner, this kinda info should always be at you, and if anyone else is getting the info, you should change username and password after they are done. This way they can't reenter your files.

You will only be able to upload via FTP unless he has installed a filemanager for you.