The 4GB limit refers to the file size, and not to the number of pixels in the photo, so your "10megapixel" photo will be much smaller than 10megaBytes in size, and you can see the file size in (for example) Windows explorer.
If you're posting straight from the camera and don't want to postprocess, I'd suggest saving in the "standard" picture quality (the 2nd pattern below) instead of the higher quality one (the first pattern)
If you do post-process, when you save as JPG in your software you'll see a way to adjust the quality (that is, the compression) of the saved JPG. I'd start with a quality perhaps 80% of the maximum, and see if that gets the file size below 4 megaBytes
I believe the file size restriction is only temporary, and will be removed after the planned transition to a larger server
Good to see you posting here
Sherm