Highlight and noob questions

[Denisgsv]

So im like very very new trying to learn vim and started with pretty colors, first anyone knows how can i make new color "gruvbox" STICK after i exit and renter ? Was difficult for me to add it in the first place , now need to make it remain.

Second such line highlight at the bottom, can it be added ? is it difficult ? do others find it not necessary ?

https://i.imgur.com/8Mfr86z.png