Can't find any instructions showing where to install the fastners and which type of fastners to use in the different positions. I guess there should be fastners of different type on the body and on the dash cover.
Photos showing the correct installation of fastners on the body?, doors? and dash cover? would help a lot
Thank's in advance

 

Different covers have different instructions, they aren't all the same. Mine came with instructions, your's should have. Have you tried contacting the folks you bought it from? Also, I took mine to an upholstery shop for installation. It costs a bit more but it will likely be cheaper than having to fix a mistake.