I am neither and expert and nor a Guru but hope this helps:
There are two parts to your problem - 1) how to read data from external webesite 2) how to display in portal
If you can write a java code to read the data and store it in the DB then you are good with that, for 2nd part once your data is in DB you can write a business service and use that in a zone/portal. If you want to do it more FW way then design an MO/Bo for your external data and then create a to search portal for the BOs. again your Java code should now read the data from external source and add BOs and rest all can be done without any coding.