when you look under your picture then you can see there "Add Tag". click on it and write vector there. tags characterize your work ...i mean when you do vector art then you will tag it as a vector, when you take photos you will tag it as a photography, when you draw you will tag your work as a drawing ...etc
you can add tags while you are uploading your work too, there is this option.
when you add tag "vector" to your work then it will add your work to category vector and people will find it more easy and you will get more views and comments :)
hope i explained well and you can ask me anytime whenever you need help :)
have a nice day