The simplest way to use a frost blanket/row cover is to just wrap it around a plant like I'm doing here. It does help if you have someone to help when it is windy!
Dalita's peas being covered while a breeze is blowing
In the case of Dalita's peas, the vines are tender and the weight of the clothes pins drags the cloth down and somewhat compresses the vines. They recover quickly once you take the wrap off but if you need to leave it on for multiple days it could be a problem.
Rocks were used to anchor the cloth to the ground
Clothes pins anchor the loose end to the rest of the blanket
The other easy way to use a row cover (no construction necessary) is to spread it over a bed like I've don on Bed 37 (Master Gardener Bed.) However there are drawbacks to just laying it on top.
In the case of the MG bed, the Frost Blanket isn't really wide enough to cover all the mature broccoli and collard plants in the entire bed. The blanket is only 6 feet wide and there are tall plants throughout the entire bed. This means the frost blanket will have to be cut in two and anchored down, folded over, pinned together, etc to make a seam. It can be done but it is harder.
You can use a sheet but sheets are heavier and compress the plants more. Also, if there is wind it will flap and beat the plants up more than a special light weight row cover/frost blanket will.
Use rocks, landscape pins, etc to anchor the row cover down on all sides and ends.
Notice how the back side is not really covered! This is a staged picture.
