There are alot of places you can get the liner and the underlayment. I did what Bonnie did as well, but ended up with my local nursery for liner. The reason is that my nursery would deliver the liner and put it where I wanted it, which in my case was my back yard. A lot of the online deliveries, will drop the liner in the street and it iis up to you ro get the liner where it needs to be - this for me was difficult as I have back problems and my DH is disabled and it is difficult for him to get around.
Figure out where you want your pond, mark it by putting a hose on the ground to the shape you want your pond to be. Measure from there.
