mint 17.3

from last time i remove kde desktop i seen this i don't know what is that,i click it and definitely it not linux mint:)))i sure i'm not install it On my lap it have lightdm and gdm3 i don't know two of them have any relationship with that

I'm trying to install the NVIDIA Linux Driver x 86 for the GT 740 card on my Mint 17.3 system. I'm assuming that it's a binary file. How do I install it?