How to merge branches with Subversion

Hi,
Idea's documentation misses page about Integrate File (Directory), hence I would like to ask this way how to correctly merge with Subversion.

I know I need to have branch where I am merging into as working copy, but I am not sure what to put into Source 1 and Source 2 in Integrate dialog. Where to put branch I am merging to and where to put one I am merging from? Or should I state branch I am merging from in both sources, but diffrent revisions (e.g. 15334 for Source 1 and HEAD for Source 2 meaning that all changes made in that time range should be considered)?

The branch I am merging from was created 2 months ago from branch I would like to merge into.

Thank you for your help.

Pavol