Size? Format?
Use picture resizing software and stick to jpeg.
I usually upload them to my albums first and then inset them in my threads.
Yeah I've created an album and gone to use it the same way I had for years but it said I had no photos to post. Boots me out and I have to login again. I've had it explained that I need to get my 50 posts 1st.
God its been a long time since I was this new lol