Spend vs. waste

To spend time is to use time. For example, "I enjoy spending time with my friends." or, "I spent a lot of time on that project." We use the same verb with money.
To waste time is to use it in a way that has no value. For example, "I wasted my time waiting for the bus when I should have taken the metro." Once again, we use the same verb with money. For example, "Don't waste your money on this product because it doesn't work!"