It's good to see you here.
If your income is only from Google AdSense then forget about Service Tax.
Service Tax is collected from your client for any kind of services you are offering them. In India its 14.5%, that means you have to collect 14.5% extra on the service you offer or else you would have to pay from your pocket.
Income TAX is paid on your gross income. Lets, suppose your income is 5L per annum then you will deduct all the expenses and come to some net profit, lets suppose 3L.
You have to pay TAX according to the SLAB rates mentioned.
Do let me know if you have more doubts.
It's pleasure clearing your doubts.