migration from 11 to 12

Hello

in order to reduce the DB offline time during the migration from our DB 11.2.04  to 12.1.0.2 . We would like to create a Master /Slave configuration. The Idea is to put the actual DB 11.2 as Master (R/W) and create a new instance 12.1.0.2 (as Slave) with a replication of all the transaction from 11.2. to 12c . Where Can I find documentation about these steps please ?

we uses Linux x86-64  RH 6.4.

Thanks regards

giorgio