Installing E3D v6 extruder electronics on Ultimaker Original+
I'm not certain exactly what you're asking, but I'll give this a try. If I've misunderstood, please give more details.

It sounds like you're upgrading to the E3D v6. If so, the heater, thermistor, and fans should connect to the same places as the previous ones did. The exception would be if you had thermocouples instead of thermistors before; that's a more complicated change.

If the connectors are different, you'll need to get matching connectors from a parts supplier (post a picture if you're having trouble identifying them). Fortunately each of the items you mentioned has 2 wires, and for the heater and thermistor polarity doesn't matter. 

For fans, polarity does matter, so match up red vs. black, or just try it one way, and if the fan doesn't turn, then swap the wires. Some fans have a third wire, which could be used for measuring the actual rotation speed (see [http://pcbheaven.com/wikipages/How_PC_Fans_Work]); but it's not necessary.