Now How to setup chained paypal?

I have finally been able to get paypal express to work in marketpress.

I have global turned off;

I want to tackle chained paypal settup and keep seeing something referring to an x.com site?

I would like a current link to tell me exactly what I need to do to get the chained option working.

I have watched videos etc. Just a clear step by step guide would work.

Thanks
Cheri Faline