Anyone know how to upload pictures of the covers of manga into an album?

Create an album.... Then tap add photo... Then again tap photo... Then you'll get a notif..... Allow, of u r using chrome, chrome to access.... Then access the pic..... Then choose the pic u want to upload.... And when it will get 100%....then tap save....
Or check this out... It have some details...
http://www.mangago.zone/home/album/151530/

If u mean how to add a cover to album then when u press add picture, select your picture, then click around the description of picture you want to be your cover and then a black bar should show up saying “COVER”, click the black bar again until it says “CANCEl” and then save