Question
I have a small side area I want to hide. The house is on one side and a wooden fence is on the other. The ground surface is cement. How do I attach the fence posts to the house and cement ground surface?

Answer
Cut the post to fit and attach the post to the house with lag bolts. (Make sure you leave an inch clearance at the bottom so the post doesn't wick water from the ground.) If the post are 4x4" (actually3.5") get a 6 to 7" lag bolt and pre-drill holes in the post and exterior wall of the house. Then squirt some clear silicon caulk in the hole of the house and screw/bolt the posy to the house. You'll need 2 or 3 hot dipped galvanized bolts.
NOTE: Make sure to check and see if it is likely there are any utilities in the wall where you are considering placing the post. Corners are the safest and you need to be sure you are screwing the lag bolts into the framing behind your siding material, otherwise it will not hold.
If you are not comfortable with this, you should excavate the area near the wall where the post would go into the ground and chip a hole through the footing as necessary so you can place the base of the post 18" or more in the ground. (NOTE, you must use nothing more then hand sledge or hammer to do this as you want to be sure you don't crack larger portions of the footing.)Thinset the post plumb with the house and pour concrete around the post and make sure post is plumb with house and 4" or less from the wall. Once it sets it will hold very well.

As for setting post where there is already concrete you have several options.

You can hire a concrete cutting company to "core drill" the concrete using a 6" dia saw/drill. Can cost a couple hundred dollars or more.

OR You can rent the equipment form a tool rental place and do it yourself. (need to be reasonably strong, honestly this is not a job for persons not of 100% sound physical condition)

Or you can get an old skill saw(not new because it is going to get really dusty/dirty) and then put on a masonry cutting blade. If the concrete is a 3-4" slab you can use the skill saw to cut 4 small cuts about 8-12" long each forming a square with intersecting corners. Then chizzle and bust out the concrete in the center with a small hand chizzle and hammer.
Once this is done you can use a post-hole digger or hand shovel to excavate the soil below to set the post. I have done this myself. It was easy but it is only good if the concrete you are cutting does not need to stay pretty because this method is kind of sloppy looking when complete.

Lastly, if the post will be supported at the top by other means and does not require strength from flexing side to side you may simply anchor the post to the concrete with a post anchor. Most Home stores offer 'Simpson' post anchors. You can drill a hole and glue the anchor in using two part construction epoxy. Then set the post in the anchor and screw it in. There are literally ten to twenty types of post anchors.

Try googling "post anchors" and "attaching posts to concrete"

Good Luck with your project.
Sean J Murphy, LA,ISA, LEED AP
Please check out my blogs and articles on landscape topics like this on my websites.
http://www.seanjmurphy.com
http://amenityarchitects.com