You may never need to edit your photos; if you’re using a CMS like WordPress, you may only need to download the original, upload it, and let WordPress do all the resizing and cropping for you.
Sometimes however you want some close control in how photos are cropped, and it may be better to edit them manually before uploading. (As your web designer for the exact dimensions)
You may have a graphics package such as Adobe Photoshop already. If you don’t, a good, free, online tool for simple resizing cropping is BeFunky.
How to crop and resize photos using BeFunky
Go to BeFunky.com and click the Get Started button. Then click the Upload button, select Computer, and find and upload your photo from your hard drive.
Let’s say you’ve uploaded a portrait photo, but you want to end up with a square photo that is 500px wide by 500px high.
Click the Crop button on the menu.
Change the Aspect Ratio in the Crop Settings to Square 1×1.
Drag the square overlaid on your photo to the portion of the image you want to be visible. If you’d like, drag its edges or corners to resize the square; press Shift as you do so to make sure it stays square.
Now click the Tick button on the left.
Your image is now cropped, and should be the right shape. You may still however want to make the photo smaller in absolute terms, to reduce its filesize – if for example you have a 3000px wide photo and only need it to display at 600px on your website.
To do this, click Resize on the menu. Then enter the width and height you want, and click the tick button.
All done. Now you just need to save your photo to disk again. Click Save on the top menu, and select Computer.
Enter a filename, and select JPG as the format (if it’s a photo with many colours; use PNG for a logo or illustration).
And click Save.