Grrr!

So I removed the picture at the top, because I was going to put a new one up, but now it's telling me that I've ran out of picture space. If I removed it, then why aren't I able to replace it? I was then able to put a new post up. So I tried to put the picture at the top, again, but it is still telling me that! I guess I'll have to try again later? I hope it'll let me put one up!