Need WP Help!

I am trying to figure out how to display only a portion of an article / post of each displayed post on my homepage (landing page). I have my ads displayed everywhere except the homepage, but if the person can see the entire article without clicking to go to it's page, then what's the point? Does anyone know how to only display perhaps only the first 25 - 50 words of an article? Thanks.

how can i see your blog dude. we need to see it so we know what's the problem