How to map in hammer with two games?

How do i do to start hammer with for example both ep2 and css? (i have got both of them)

When i just change the “Current Game” in source SDK all the textures i’ve added goes white.

GCFScape

Download that, then extract the CSS gcf which should be found in steam/steamapps and dump it all into your ep2 folder, or the other way around. Then start it for the game that you dumped the files of the other game into, if that makes sense, and you should have the textures, props and entities for both games.

I think.

You’ll also need to edit the config for Ep2 to include the CS:S entities (if you need them)

Thanks!

Edit the config in exactly what way?

No. Simply add the CSS .fgd in hammer options.