500px Advice

[DuncanP]

I have just opened an account with 500px and have started to upload photos using the trial Awesome membership. I wish to put my put my photos in the store but I am unsure how to set the aspect ratio. Is there a tool which shows or is there an easy method in CS3?
Thanks

 

[DuncanP]

I usually crop my photos and was wondering if there was a tool which would allow me to select the nearest allowable aspect ratio.
I thought that I had read somewhere that 500px had a tool for this but when I go into the edit photo option, it just displays the picture with no toolbox.
I suppose that I could try to write a program to do it.
I have just started with 500px but if you want to see my photos search for "Duncan Paton".
Thanks