Please read the manual. not knowing this means you have not read the manual.
you can find the manual here:
http://usfirst.org/roboticsprograms/...nt.aspx?id=452
under section 2, The Arena, you will find the dimensions for the zone, lanes and much more.
Some information is lacking from the manual, such as height of pegs. this information can be found under the "field drawings" section in the above link.
Good luck.