To upload a picture, the process is slightly different if you're creating a new thread, or adding a picture in a comment on an existing thread. On a new thread, you don't need to select the "go advanced" button mentioned below, as you are already in that screen, so just skip that step and otherwise it's the same process.
Select the "go advanced" button below, then scroll down to the "manage attachments section. Select your photo, then press upload. Once the upload finishes, close the window and select preview to verify the picture is there, then post. I see picture attachments frequently from first time posters, so I don't think there's a number of posts requirement for that. Other stuff, like setting an avatar picture, will become available as you increase your post count.