Perforce branching is pretty simple.

Say you want to create a branch called

//depot/fkim/foo

First you would add it to your client.

//depot/fkim/foo/... //fkim/foo/...

Next you would do an integration from where you wanted to cut the branch.

p4 integrate //depot/work/foo/... //depot/fkim/foo/...

Then you would submit the integration and the branch will be created and updated in your client work space.

p4 submit