Fluval filters are great, I've got the 204 model and I've never looked back, way better than any internal filter. Your Fluval should have come with some biological rings that you put in one of the baskets, once you start passing water through the filter the bacteria will automatically establish themselves on these rings as water passes through them. Your Fluval will also probably come with a carbon media and the actual foam spunges too, infact everything to get you started.
Just one word of warning never ever lift up one of the side clips which holds the top of the filter to the main bucket area while the filter is still switched on. I was worried one day that the clip wasn't securly locked into place so I went to lift it up in order to reclip it down. Once I lifted the clip; up water gushed everywhere and soaked the whole living room, which was made worse by the fact the pressure is so strong you can't then get the clip back down. Lets just say it wasn't a pleasent experience and I dont reccommend anyone else try this.