I haven't found any single on-line source that gives a good introduction to the notion of algorithm, though there are many sites that talk about specific algorithms. You might find it helpful to browse through some of these.
The word algorithm itself is defined in lots of places; an interesting take on this is to use OneLook to search for the word in a bunch of on-line dictionaries, then read entries that seem interesting or relevant. This definition is better than average. You can also use Google to search for various forms of algorithm. Google is the best search engine by a wide margin, so it's good to know about anyway.
In class, we will be talking about only a handful of the most basic algorithms for searching (finding things) and sorting (putting things into order).
Searching as we cover it in class -- linear search and binary search -- is sufficiently elementary that it doesn't appear much on the web. If you look for phrases like "elementary searching algorithms", you will narrow things down a bit.
There are quite a few web sites devoted to sorting techniques, often using animation to show how specific algorithms work. This site gives a static textual description of three simple sorts, two of which (selection and insertion) we will discuss in class. There's more detail than you need.
You can get some sense of how broadly the word "algorithm" is used in a computer science context by checking out the Algorithms page at Softpanorama. Well down in that page, you will find pointers to sorting algorithms, along with references to many other more specialized algorithms.