The picture was obviously taken from a DSLR. So i assumed you snapped the picture yourself.
You can use TWO methods to reduce the File Size/Resolution.
1. By hosting it on another Image Hosting Site. Use the URL to upload, and before hitting "Upload" button, use the option from which you can Resize the Pictures. Resize them to an appropriate level, 1024x768 etc.
2. By downloading the Image, and Reducing its size yourself. You can use Win7's Tool (since everyone these days are using Win7) called Image Resizer