How to secure transaction console for ERP

HI ,

We are trying to secure the transaction console for some invoices transactions and create a role to give access only to those transactions, we tryed follow a guide when open an SR but it didnt work and the suport suggest that the corret place to ask for this help was here.

1) How to secure the transaction console?

2) What kind of access i need to give to a employee to only see Requisition Approval,Purchasing Document Approval,Invoice Approval.

Thanks in advance