Open the window, such as Internet Explorer or Adobe Photoshop, that contains the work you wish to display in your portfolio. Take a screenshot by pressing "PrtScn" for Windows or "COMMAND + SHIFT + 3" on Mac OS X systems. Paste the screenshot into a graphic editor, such as Paint using "CTRL + V" on Windows systems.
Sketch out the size of the initial view (what can viewers see without scrolling or viewing a new page) on a piece of paper. Decide how many pieces should fit within that space. Add margins and spaces between screenshots according to your preference.
Calculate the width of each screenshot by subtracting the measurements for the margins and spaces from the measurements for the initial view. Divide by the number of screenshots you want in each row or column.
Open the graphic editor into which you pasted the screenshot. Click "Crop" and enter the dimensions for the space in your portfolio in the "Height" and "Width" fields. Check "Keep Aspect Ratio" and click "OK."
Drag the corner of the crop selection tool to expand the size of the selection. Position the tool over the portion of your screenshot you want to highlight in your portfolio. Press "Crop" again to remove the unselected area from the screenshot.
Click "Resize" in the "Edit" menu. Enter the dimensions for the space in your portfolio in the fields for new "Height" and "Width." Press "OK" to resize the screenshot.
Press "Save As" to save the screenshot. Keep all saved screenshots in the same directory for easy access when loading them into your portfolio template.