As mentioned above you will have to send your space station up in stages. Something like this: 1st Stage, command module (manned), accommodation etc, 2nd Stage, command module (unmanned), refueling post, docking port/s on side for spacecraft to dock to, 3rd Stage, anything you want! Try to make sure that there is only one Kerbal aboard the station while it is being built (like Jebediah because he is always happy), also, when you send the refueling post make sure it is empty and then send up a Supply Services ship to your space station with more Kerbals and fuel to transfer - this is what the SpaceX Commercial Supply Services flight to the ISS do.
