For screenshots:
You can take a full-desktop screenshot by pressing Print Screen -- Windows will Copy it to the clipboard for you. Then just Paste it into Paint or another image editor app, save and you can upload screenshots to
imgur.com without even having to sign up for anything. imgur then provides links you can use to show the image here or elsewhere.
For videos:
You will need to decide what you want recorded because different apps will record different things. Some will record a Direct3D game, these work fine but in that mode it will not capture any ISBoxer
Video FX or additional windows. To get Video FX in the video, you need to make sure DWM layers/composition is recorded.
* I use
CamStudio when I want to get down and dirty with something free. It's definitely not the best, actually it's kind of a pain but it does work
*
FRAPS is used by many pros. I think MiRai uses FRAPS. To record vfx with FRAPS, I think you want to set it to record the desktop.
*
X-Split should also work I hear
*
MSI Afterburner also has really good video recording but I am not sure whether it can capture Video FX. It will capture high quality video from all of your windows at once though
As far as processing the video and making it look good with added text, I'm not the one to ask how to make it look nice
Professional video editing software is the way to go as far as I know. Maybe someone else has suggestions for that part