2nd questions

I created a topic just now but it shows"this topic is unlist, not be displayed in topic lis…".did i do something wrong?
I have 4 questions to ask but it warns “Sorry, new users can only put one embedded media item in a post.”then i tried to list rest 3 questions in reply howevery it shows"Sorry you cannot post a link to that host."
to make clear all questions i decide to create 3 more topics to ask it,this is second one.
2.what’s the logic of store?This building
no matter what i do,building wanggong stock-yard or what,the 3rd line keep like that.how to reduce the time cost on store?