I added more channels on my television but they wont come on

Just because you added them don't mean that they are available or broadcasting. First of all where are you getting the signal from. Cable or over the air (antenna) ? If you are receiving over air free TV you may not have a strong enough signal. The best way to add channels is to do a scan and let your TV find them automatically. For over air broadcast sometimes your TV will find channels that are not quite a strong enough signal to play depending on your location from the the station transmitter. Note that relocating the receiving antenna or getting a better one will usually fix this problem.
Now if your receiving Cable then you have another issue.
The only channels that you will be able to receive directly with your TV is the ones that come with the basic service the rest will be scrambled and will require that you pay a subscription an be connected through one of there box's which contains the descrambler that can turn on or off from the cable company office.
Hope this helps.