LinkedIn requires a logo. The file format must be PNG, JPEG, or GIF, and the memory size of the logo cannot exceed 100KB.
You can design your own logo at sites like LogoYes and LogoWorks . If a logo already exists, like for an alumni association, ask one of the administrators for a high-resolution copy of the logo, or save a copy of the logo from the group’s personal website, as long as you know you have the rights to use that image, of course.