no; it will do it for you. Be sure to choose resize/create thumbs on upload in the dialog window. If your images are huge like 4mg... just be patient and try not to choose to upload like 100 of them at once, for images that big, it work better to do them say.. 10-15 at a time. For me when I upload a bunch.. I usually run a bulk image resizer on them and get them down to 1980px; it just makes everything work better cause they are not as big Mb wise. I used Fireworks for this... I know everyone doesn't have it and can't afford it, so you can google "free bulk image resizer" there are a bunch out there... I don't know which is best.
