I would appreciate if you help how the tissue is sent
In all seriousness, based on the majority of textures on GraphicRiver, you should upload textures that are at least 3000-4000 px on the shortest side. You can upload JPEG or PNG for general use. If you want to make the textures tileable, then it might be a good idea to also supply a Photoshop PAT for the easiest use.
Take a look at the different items in the category to get a better idea on what you should supply. The specs are on the right side of the item pages.