Photo Sharpening for Group Picture

I have a JPEG photo of three people in a group, which is moderately out of focus. The image primarily centers on people's faces, with particular emphasis on the person in the foreground. I need help bringing it into better focus for personal use, as it will eventually be included in a projected slideshow.

Ideal skills for this job would include:
- Proficiency in photo editing software
- Experience with image sharpening techniques
- Attention to detail, particularly in focusing on faces

I hope to have my photo looking its best for the slideshow.