Hello there! The girl download is in the grey box that says girl version, you have to right click and save the tiny image. If you don't know how to change your skin using an image I'll explain it below:

Once you have the small image go to minecraft.net and login. You should see your email with an arrow next to it in the corner, click on it and then go to profile. You should see something that says "Classic (Steve)" click on it and choose "Slim (Alex)". Alright now there should be a big grey button under that which says "Select a file" click on it and choose the small image that you saved. You should see the small image there and then "Upload" underneath it, click on that then you're done!

Thank you! :^>