TBADDBITMAP nID member

I was wondering, what are the dimensions of the bitmap like the STD_FILENEW you would use for a toolbar? Also, if you made your own bitmaps, would you just assign the nID member's value the ID of your bitmap you want to use? I don't think that's right because MSDN says: "Resource identifier of the bitmap resource that contains the button images.". So it doesn't look like just a regular bitmap you would create that is just one big picture. So basically, what steps would you have to take to tell it to use your custom button images? Thanks.

Toolbar images are discussed here.

This displays blank buttons:

Code:

    TBBUTTON tbb[2];
    TBADDBITMAP tbab;
    SendMessage(hTool,TB_BUTTONSTRUCTSIZE,(WPARAM)sizeof(TBBUTTON),0);
    tbab.hInst=hInstance;
    tbab.nID=TOOLBAR_ICONS;
    int iOffSet;
    iOffSet=SendMessage(hTool,TB_ADDBITMAP,5,(LPARAM)&tbab);
    ZeroMemory(tbb, sizeof(tbb));
    tbb[0].iBitmap = iOffSet+0;
    tbb[0].fsState = TBSTATE_ENABLED;
    tbb[0].fsStyle = TBSTYLE_BUTTON;
    tbb[0].idCommand = ID_FNEW;
    tbb[1].iBitmap = iOffSet+1;
    tbb[1].fsState = TBSTATE_ENABLED;
    tbb[1].fsStyle = TBSTYLE_BUTTON;
    tbb[1].idCommand = ID_FSAVE;
    SendMessage(hTool, TB_ADDBUTTONS, sizeof(tbb)/sizeof(TBBUTTON), (LPARAM)&tbb);

Did I miss something?