That should have been very easy, now that you know what each part is used for and where they go. If you think about it building a computer is really just a step up from making something out of legos. You just simply snap the pieces together. Now if you have hardware that is not compatible with your system there is nothing that you can do about that. Because every motherboard is different, you will have to check the manual to make sure that everything you are trying to put together is compatible and how you should go about doing it. By now you should have some extra cables and parts laying around, don't worry. Every part should have come with everything that was needed, therefore you will have some extra cables left over, since your motherboard also comes with a ton of cables and such.
Depending on the parts that you used to build your new computer you can expect it to anything within it's limits. If you went cheap and did not spend a lot, don't expect do to much as far as playing all the new games, and burning CDs in a flash, or whatever else a powerhouse PC is capable of doing. If you are just using it for the internet and business pretty much anything out there will get you by.