No button download upload plugin

Hello !

I’d like to change the theme on a old blog. But there is no button to upload new one on Apperance, no editor.

I’d like to upload new version of WordPress to 4.5.2, but there is no button to install it. I’m not an informaticien ,-). I’m not user-friendly with code and FileZilla ! Could you help me please ?

Thanks you so much from France 😉

– I don’t find how to upload WordPress in 4.5.2

– to download theme

– to download plugins (https://fr.wordpress.org/plugins/wp-construction-mode/)