you need to use the 'edit' option in the programme you use to view your pictures.
Then when you have opened it in the 'edit' mode (i.e right click your picture and it should give you a list of things....choose 'edit'), there should then be an option from the 'image' drop down menu at the top of the page to 'strech/skew' your picture, choose this and put in 25% into the two boxes within the top of the box, apply that then save the image with a new title, such as 'nail pic smaller'.
By doing that, you should of then reduce the file size of your picture, so that it will upload onto this or any other site.
Check the size of the picture by right clicking, choose 'properties' and that should tell you the file size.
For us to be able to see the image clearly, you need to have taken the picture with the 'Macro' setting on your camera - usually identified by a flower symbol. This enables close up, detailed photos.
Phew! Hope all that makes sense hun!!