I'm using Egit

There is an online repo (we'll call it "Repo_Origin") and
I clone "Branch_A" from it to my removable USB drive as "Repo_Portable".
Then I clone Repo_Portable to my local HDD as "Repo_Desktop".

How to set up ref specs and what operation do i need to perform to;
1) Push new changes (commits) from Repo_Desktop to Repo_Portable
2) Get latest updates from Repo_Origin to Repo_Portable
3) Get latest updates from Repo_Portable to Repo_Desktop

I'm having some trouble with this, not sure if it's the operation i'm doing (pull / fetch / force update?) or if its a wrong ref spec configuration