I would like to know how to have a jpg file appears to be a little bit clearer and bigger if I insert it on word 2007.
I used snag it to capture a file and it looks good actually but if I paste it on word, then it became small. Any idea?
Word inserts the image in the size the image has. When you make a screenshot and the tool you are using specifies in the image a resolution of 300 dpi, then it's going to be quite small in print. Word uses exactly that information.
Furthermore, if an image would be larger than the current bounds of the paper it will be made smaller as well to fit.
In both cases you don't lose any image information. The whole image is still there, just a little smaller. Word does not reample the image, just chooses a display dize. So you can always go back and resize the image to your liking.
The thing is a little different once you export to PDF with the built-in support, though. Then all images are stored as JPEG and resampled to (I think) 150 dpi.
Side note: For screenshots I'd rarely use JPEG. My HDD isn't that full yet that I cannot afford PNG for things I like clear and readable :-)
In Word 2003 you can right-click on an image after inserting it and select Format Picture... on the pop-up context menu. In the Format Picture dialog box that appears there's a Size tab with various controls. There's also a Picture Toolbar which, if visible, had a Format Picture button on it. Word 2007 probably has similar functionality, as well as a Help menu...