How to add an attachment with campaign


I wanna send campaign with 2 attachments. I tried a way to do that but not able to. however i have checked all permissions here.
backend-> setting-> campaigns
seems everything is fine. but not able to find option to add attachment with campaign.

could anybody help me out?

thanks in advance
Attachment not working,
I enable it and When back to check attachment not there,
i am use in backend .jpg .png .pdf no one wokring.

Can any one help me with this.?
@Mohit1946 - after you add your attachments, can you confirm they remain attached to the campaign ? (go back one step from confirmation step).
Also, can you confirm you actually send a test campaign to a test list, not just a test email ?
@Mohit1946 - You need to have extensions and mime type added in backend.
In backend-> setting-> campaigns -> Allowed extensions, add jpg, jpeg, png and then on allowed mime types add image/jpg, image/jpeg, image/png.