The main layers to worry about are:
Network layer. For the internet, this is IP, the Internet Protocol. This is an abstraction layer that allows network packets to be sent over any kind of network with a common interface.
Transport Layer. There are two common protocols here, both of which use IP to send information from host to host. UDP is a simple packeted protocol that transmits short packets of information, with a resonable chance that they will get to their destination. TCP is more complex, and provides reliable, streamed connections between the two hosts.
Application layer. These are protocols written for specific applications, such as ICMP. They run over the data link layer protocols; ICMP runs over UDP while HTTP runs over TCP. (There are literally thousands of application layer protocols).
For information relating to specific protocols, look on
www.rfc-editor.org where you will find the definitions of all standard Internet protocols, including ICMP.