[U2Lynne]

Thread subscription means it shows up in a list of threads when you click on your User CP. I think you can also have an automatic email sent once a day telling you if anyone replied to a thread you are subscribed to. I'm not really sure though since I never use those options. I don't think that is what you are looking for though.

I think you probably just want to post a thread in Lossy/Lossless and when you hit New Thread an option to Manage Attachments is on the bottom of the page. Click that to get a pop-up to attach images. If you want to post attachments to a thread that already exists, just hit the Post Reply button or the Go Advanced Button and you will go to another screen where that Manage Attachments button appears on the bottom for you to click and add attachments.