How To Set A Startup Gif On a Website For Copuple Second not for until the whol site load .

How To Set A Startup Gif On a Website For Copuple Second not for until the whol site load .

Hellow can any buddy can help me on setting a Animated Startup screen on  website for just 10 seconds just like this web , www.brightpaki.ml Please tell me how cani do that in the startup im exhausted and cannot find a way to do it . 
any way Thanks In advacne .