Jenin sits at the very north of the West Bank, closer to Nazareth than to Ramallah. From Ramallah the cheapest option is a service taxi (shared minibus) to Nablus and a change there for Jenin; the whole trip is two to three hours depending on checkpoints. From Nablus direct services run frequently throughout the day.
Israeli citizens cannot legally enter Jenin under Area A rules. Foreign passport holders can, but the security situation around the camp shifts week by week — check current advice before going, and be prepared for delays at the Hamra and Za'tara checkpoints.