I want a north face am ordering online and ont know what size i am help?answer a.s.ap please?!?

So I want a north face but im going to order online... and i don't know what size i am. In shirts im normally a xs somtimes a small in jeans im a size 0/1 usually.and im 5'1. if any of that helps i want a fleece not a heavy jacket. thanks.:)