of course there is no guide on how to post pictures, you have to figure everything out yourself
I’m happy to report that slidestr is now awesome and implements all the things. You can click hashtags and profiles and everything and it just works and it’s beautiful. Especially on desktop.
https://slidestr.net/tags/photography nostr:note1nj8cvsm538wmkfngzrj0qpjr23x8hxdjvhn00dl96gxrg0m6ws3s5ch6vt
Discussion
You can use any client to post a picture. You did it in the past, so you've already figured it out without knowing it! 
https://slidestr.net/npub1glx6mzfdtzlnsx4xvtqckzydk9q2mhmsez0k9d3z96st66r6azhslr7vv9