Assuming you are using a recent version of Vegas, add another video track above your main track. Right click on that track and select "add text media" (I'm quoting that from memory, the exact text may be different), and it will add a text media event on that track and then open the text editor so you can change what it says, the font, size, animations used to intro/hide the text, etc.

For the black frame at 1:49, go to the media generators tab and add a solid color on the same top track that you put the text on. Make it black (if you don't see how to, right click on it, edit generated media). Right click on it and go to video event pan/crop. Go into mask mode in there and make a square mask. You may have to select the option to invert the mask to get the effect your are after, but basically you'll use the mask to cut a square hole in the generated media, revealing the video on the track underneath inside of the hole. Then you can add more video tracks above that to insert the green text, the little square overlays on the center of the screen (you can make these in vegas image, photoshop, or any similar app, just make sure they have a transparent background when you do, or you can use the same generated media with a hole cut in it method I describe above to make each of the little squares) to simulate the focus points, etc.