I am currently building a pergola over a concrete slab. I have run electrical wiring (white, black, ground) from an existing GFI on the back of my house, under ground to one of the posts connecting to a GFI in a weather proof housing. From here Id like to power a ceiling fan and a switch to operate it. How do I do the wiring from this point?

Not sure what you are asking. Do you need every detail of what to do? Without seeing it that is hard to say.
Did you run the wiring in conduit?

Yes the wiring is run through conduit under ground, pops up at the foot of one of the posts, runs up the post into an all weather 1 gang box that housesw a GFCI outlet. From here I would like to use the power from that outlet to run a fan and have a switch operate its on/off functions. Not sure how to wire it from here.

Pretty Basic...
First, Why the 2nd GFCI?
Out of the new outlet box conduit to switch box (20 amp breaker, 12/2 wire; 15 amp breaker, 14/2 wire). At the switch , black wire to bottom screw on the side of the switch w/ 2 screws. Conduit new wire to fixture box. At the switch box, black wire to top screw on switch and connect the white wires (both incoming and outgoing) together. Connect both ground wires together and pig tail to switch. At the fiixture box, black to black, white to white and ground to ground.

I like conduit(PVC), romex is fine, from slab up connect to a 2 gang outdoor box(PVC) then a 12/3, if a 20 amp circuit, 14/3, if on a 15 amp circuit up to the fan location, the 12 or 14/3 allows separate light and fan control, or wire fan for pull chain operation, they make dual Light/fan controls that fit in 1 device, and have a receptacle for the second in a 2 gang box. A Bubble Cover(inuse covers protects all).
Go back to the house GFI and have it on the LINE side, NOT PROTECTED side(didn't mean to yell, it is just important), then have GFI at Post and have fan and light NOT Protected and Receptacle will be a GFI.
This allows The lights to remain on should the gfi trip, and the circuit to be reset locally, instead of going back to panel?

Thanks for the response. The reason for the "2nd" GFCI is that the new patio is not connected to the house. I made the GFCI that was on the rear of the home a junction box doing away with that GFCI all together, then ran the wiring through the conduit under ground to the post at the pergola. From there went to the outlet and that's where I stopped.

Did anything I said make sense? Or work?
I would leave the GFI on the house, and hook the new wiring to the LINE side.

Everything you said makes perfect sense and I really appreciate the help. Once I complete the run I'll re post with the results. Thanks a ton!

Good Deal. Good Luck.