Notice...

#include <iostream>
#include <windows.h>
#include <string>
using namespace std;

struct dll{
char dp[_MAX_PATH];
char windowname[_MAX_PATH];
};


int main(){

 HWND hwnd;
 HANDLE hproc;
 HANDLE htread;
 DWORD dwpid = 1;
 DWORD hmodule;
 HINSTANCE hk32 = LoadLibrary( TEXT("kernel32.dll"));
 void *praddres;
 dll d= { "C:\\TestDLL.dll", "SpellForce 2" }; // edit your dll path and your procces here
 hwnd = FindWindowA(NULL, d.windowname);
 GetWindowThreadProcessId(hwnd, &dwpid);
 hproc = OpenProcess(PROCESS_ALL_ACCESS, FALSE, dwpid);
 praddres = VirtualAllocEx( hproc, NULL, sizeof(d.dp), MEM_COMMIT | MEM_RESERVE, 0x40 );
 WriteProcessMemory( hproc, praddres, (void*)d.dp, sizeof(d.dp), NULL);
 htread = CreateRemoteThread( hproc, NULL, 0,(LPTHREAD_START_ROUTINE) GetProcAddress( hk32, "LoadLibraryA" ),praddres, 0, NULL );
 WaitForSingleObject( htread, INFINITE );
 GetExitCodeThread( htread, &hmodule );
 CloseHandle( htread );
 VirtualFreeEx( hproc, praddres, sizeof(d.dp), MEM_RELEASE );
 cout<<"Done\n";
 cin.ignore();
 return 0;
}