L.A.
Use Paint. It's probably under Accessories.
You probably can right click on your jpeg image and choose Open With > Paint.
Once you have it open in paint, you can select Image at the top control bar then Stretch and Skew. Change the Horiz and Vert to a smaller percentage and this will make your photo size (height and width) smaller and thus the file size (mgb) smaller. If you're taking a 10 mb picture, there is a LONG way you can go to send a photo as an email. I usually do 20% and they are plenty big for emails.
You can save it in another format but the quality may be degraded, or the format may not be smaller. You could also try saving it as a zip by right clicking and Send To > Compressed (zip) Folder, but this doesn't necessarily help much depending on the content of the photo.
I think there are other ways to compress them, but you'd need a program like Photoshop to do it. Make a copy and play around with the size. I'm pretty sure that will get you what you want. You can email me if you have a question.