Am i using up my data when i'm connected to the Wi-Fi at my house?

So basically i just got an iphone(iphone 4) last night and i'm worried about going over the data usage. I went to setting>general>network and then turned off cellular data. I think i have about 2 things of data to use, i'm not sure if its like gigabytes or what not but yeah. I just wanted to know if i'm using up my data if i'm connected to my Wi-Fi and the cellular data switch is turned off… Cause i use the internet a lot (tumblr, instagram, twitter, facebook, youtube, music etc.) i just want to make sure i'm not using my data if i'm connected to the Wi-Fi at my house. So thanks!

You won't use your data usage if you are using your Wi-Fi.
Wi-Fi and phone network data is different