サンプルぐらい検索すりゃいくらでも出るだろ。
include "DxLib.h"

int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow )
{
if( DxLib_Init() == -1 ) return -1 ;

LoadGraphScreen( 0 , 0 , "test1.bmp" , FALSE ) ;

WaitKey() ;

DxLib_End() ;

return 0 ;
}