You set the pools in the configuration tab, you can set up to 3 pools.  If your first pool goes down, the miner will automatically switch to the 2nd pool, if that pool goes down it switches to the 3rd pool.  Its just in case the poolside has a problem so you can still mine to another pool.

The frequency sets the chip frequency, which will change the hashing speed.  Not really a good idea to play with that unless you know what your doing.