Noob wanting to make a game

[sirtuftcat]

ok i think ill start with making a door.. i figure simple shape and hopefully easy to texture... ‎  one question i have is how big do i make the door in the mesq program? ‎  and are there more textures avaliable somewhere or do i and/or should i make my own entirely .. soo many things to take into account and whats the high res setting im after or is it just called high res.. ‎ 

lol im already lost with this 3d stuff lol