I want to buy a small scale solar panel for my house? please help

Start by thinking of what you want to do with that power first. Then figure how much power you will need. Turn it into watthours. Then determine how many hours of equivilent full rated power you can get from the Sun in your region. Example-
Lets say you want to power 3- 100 watt bulbs for 6 hours. This would be 1800 watthours.
Now lets say that in your region on the shortest day (dec. 21) a PV module will recieve 3 hours of equivilent full rated power.
Now we divide 1800 by 3 and we get 600. That would be a 600 watt PV array in full unshaded sunshine from at least 9:00 am to 3:00 pm and perpendicular to the Sun at noon time on the shortest day.
None of this takes into account the battery storge or inverters to make 120 vac from the low voltage dc that the PV modules.
One of the best investments I feel that I made when we decided to go solar was a subscription to HomePower magazine. The reader gets to see various systems installed as well as rendered schematics and he or she becomes familar with phrases and terminologies and what they mean by reading the articles and reports and all.