When you buy it, you get better instructions than these - but ...
You can lay it right over your old linoleum or vinyl flooring.
First you remove the shoe molding from around the room (not necessarily tthe whole baseboard - just the 1/4-round molding at the bottom)
Then you put down a foam pad (this is to dampen sound and keep the floor from moving.)
Then you lay down the floor, which comes in pieces that are (not sure about dimensions) eight inches by 3 feet. The pieces are tongue-in-groove and join together with a special glue. Of course, cutting the pieces to fit around obstacles make this a little easier said than done, but still not a major difficulty.
The floor just lays on top of the foam pad and "floats." So you do not have to adhere the pieces to the subfloor - just to each other.
Also, a 1/4" gap should be left around the perimeter of the floor to allow expansion. This gap is covered up by the 1/4-round molding and/or baseboard molding that you removed in step 1.
I did my kitchen (floor space about 10x12) in one (long) evening.
The only special tool you REALLY need is a metal "L" that is used to allow you to hammer the pieces together without damaging them. You can buy the tool and some spacers in an "installation kit" for about $20. You can buy more elaborate installation kits also (for more money) - they certainly do help make installation easier, but aren't totally necessary. (they include strap clamps to really tighten the joints.)
You can buy videos and books to learn about the installation. Here are the instructions at the Pergo website: