Recommend in Windchill you create ACLs by Role or Group, not by User.
If you have multiple organizations in your Windchill system, suggest you create ACL at the organization level. Do you want the ACL to be available within every Product or Library Container in the Org? If yes, create the ACL in the /Default (your org)/PDM domain. If No, then you want to create ACL in the Product or Library Containers.
1) Log into WC as org admin
2) Open "Browse" tab
3) Click on Organization Icon and select "Utilities"
4) Select "Policy Administrator",authenticate to the pop up window.
5) Click + sign to expand Default (organization - your org), click on PDM (organization - your org), then click the "Update" Command Button.
6) In the "Administrative Domain" GUI, select "Access Control" tab, click "Create" command button to create your new ACL.
7) In the "Access Control Rule" GUI, click on "Help" and it will explain the rest of the steps for you. 