The Cat 5 standard has been updated to the Cat 5e standard. However, the crimping configuration remains the same, so these instructions will work for either standard.
There are some excellent additional tips and elaborations on procedure in the comments, so I'd recommend that you read those too as you go through these steps.
Step 1: Materials
~ Cat 5 cable
~ 8P8C (8 pin 8 contact) connectors - (these are commonly referred to as "RJ45" connectors)
~ A modular connector crimping tool
~ Wire cutters/strippers (may not be needed depending on crimping tool)