Hi can anyone tell me how I get cass to follow me to freeside to see baptisste?

You need to go visit Alice Mclafferty at the Crimson Caravan Company.

You need to do the quest that gets her to follow you in the first place. All companions, well, most companions you need to do something before they will be your companions.

Talk to Alice at the Caravan company. It may help to go through all the dialogs with Cassidy first as she tells you this if you talk to her.