Blog problems

Hey everyone! hope you are all doing good! As you see I don't have a cute little header on my blog. :( I was trying to change my header because I had made a new one and was putting it on my blog and it kept saying invalid url. Now no matter which header I try to put on there it says that. Is anyone else having problems with their blog? So for now I guess my blog won't have a header. :( Well on a different note...school has started and is going really well! It is still kind of hard getting back in the swing of things but I am getting there. I like middle school alot so that is good. Well I guess that is all for now! I hope everyone has a great week!! :)