You can take screenshots by two methods:
1) Either press the print screen key on your keyboard while in campaign to capture a screenhots in .tga format. Your screenshot will be saved in the
tgas folder in your main M2TW directory.
2) After that download a photo editing software like
GIMP and then open that .tga file and use it hide your HUD showing faction icon and such somewhat like this:
3) Save the file as .jpeg or .png type & then use a image hosting service like imageshack or tinypic to upload your screenshot and then paste it in your post by providing its URL address in the insert image icon box "
"
Alternatively you can download
Fraps to capture a screenshot and then edit the saved screenshot using MS paint.
For capturing a big view of your radar map read
this post to capture screenshots in bigger resolutions, then just use the crop tool in your photo editor program to get only the desired area separately.