There are two methods to connect PEX that don't require a plumber's license. Both methods are easy and neither requires specialty tools or a plumber's license. In this video, professional plumber Bruce Norman demonstrates how he uses a generic crimper and clamp rings to connect PEX-to-PEX or existing pipe, as well as how he uses a user-friendly SharkBite push-fit fitting to make PEX-to-PEX or PEX-to-copper connections. The latter method is especially useful for making quick repairs.
For more information on working with PEX, read Making Basic PEX Connections.