The simplest version is a UNC repository and it also depends on what resources you have but the best way is to have a server or NAS box at the remote branch to host the repository. Bascially a windows share that avalaible 24/7 and accessible by all clients at the remote site.
The idea is that you really want to replicate the repository overnight rather than through the day. As even the smallest incremental replication is going to be 100-150Mb because each day Mcafee with release a new incremental DAT (300k-800k) and the rollup DAT avvdat-xxxx.zip (120Mb). Depending on your bandwidth between the master repo and the distribution one you need to estimate how long it will take and schedule accordingly.
I have toyed with other cheaper solutions like the small network devices that allow you to insert USB sticks and share them on the network.
and you can get similar cheaper devices.
As far as the repo itself in ePO simply go Menu -> Software -> Distributed Repositories click 'New Repsoitory' down the bottom and fill in the details.
Once the repo is created you then need to create and replication server task (there might already be one there that you can enable and re-configure) this will perform the actual replication and the scheduled time.
Another option is to use super-agent with lazy caching but seeing as you new to ePO i would suggest cutting your teeth on a UNC repository to start with.
Thank you very much.