This is a rough description and not a detailed
step by step.
Create a small part of the net with decent detail (or more if you can ). Get the shape nice and clean so it can be "tileable" and copy it around to make the net.
You have to end up with one clean mesh, all vertices merged, dont combine things.
Then render the plane using the orthographic viewport that is looking straight at it. The camera option "Resolution gate" will help you define the size of your rendered image.
That Image then can be applied as a texture to a poly plane of the same size, and since it will have alpha channel, it will have transparency auto connected.
For the poly plane you can use the transfer maps (under lighting rendering ) to make a normal map, using the net you did as a source (this is a big deal to type down, look for a tut ).
Now to make it deform... up the resolution on the poly plane, make it a soft body and use springs between the soft body particles (again this has sooo many details ). That way it will also behave like a net. This is the part where it will take the shape of a net, look like it's hanging in the middle but also tense and stretched.