So, we need to get our images in the acceptable format to our content and our social media guidelines.

There are a few image resizers that you can use online for free, here is a list below:

• http://resizeimage.net/
• http://resizeyourimage.com/
• http://www.resizeimage.4u2ges.com/online_image_res...

I have personally used the first one and it is fairly easy to use. Like anything else, you have to try it out and see what works best for your purpose.