You already have it. Paint. Good old Paint. Copy the image/screen. Open Paint. Paste the image in. Save as .jpg or .gif.
If you see an image on your screen, with a cursor on it, right click your mouse. This should bring up a menu with should have an option on it to “save image as”, or words to that effect. Most images are either .jpg or .gif format.
If you see .htm, .html, or something like that, it is trying to save the entire web page, not just that particular image, so you should check your right click again, to make sure it specifies save “image” or “picture”.
there is no conversion from html to image file formats.
html is a language... hypertext markup language.
If you want to convert a viewable web page into an image,
the best way to do that is with a screenprint.
You should have it as a key on your keyboard...
when you press it, it creates a bitmap image of what
is currently displayed on your monitor and places it into the clipboard. (system memory)
Once you take a screenprint, go to paint, click on the “select” icon (top right corner of tool bar), and while your cursor is over the paint area, right click and select paste. This places the screenprint you took from the clipboard into the paint application.
Now you can save this as a bitmap, gif, jpg, or whatever other format paint offers.
You can open your .gif file and then "Save As" form the drop down file type. then pick the bmp, gif, png etc that meets your needs.
If you are saving from jpg to bmp your will be told that some of the values will not be saved since you are using a "less values" file!
Good Luck.
On Windows, try downloading Paint.net. It is a more powerful program than windows paint and it’s free.
You can also try Picasa, a gallery and basic editing application from Google.
http://picasa.google.com/#utm_source=en-all-more&utm_campaign=en-pic&utm_medium=et
If you have a Mac, iPhoto should do what you need.
Try Webshot. It will capture a web page (html) as an image.
http://www.freewarefiles.com/WebShot_program_24215.html
If you use Firefox browser, check the add-on/extension called Screengrab!
It will save web pages to image files.
https://addons.mozilla.org/en-US/firefox/addon/1146