There are three basic knots that should be the first ones you learn if you're gonna try macrame. First, we've got the basic square knot - it's like tying your shoes.
Then there's the half hitch knot. This one is basically just looping one cord around the other and pulling it tight.
The third knot is the double half hitch knot. This one is like the half hitch, but you loop that cord twice around the other one before pulling it tight. You can make some great designs with just these three basic knots.