Have you read the
wiki? This baiscally just rewrite the relevant bit, but here goes anyway:
Rightclick the ram. If the option comes up to move it, select 'move', and when your cursor changes (looks like the 'lift' one) click on the bit of wall you want to demolish. When it's moved to the right place (if it can get there), rightclick again and select 'use'. Then get up to three of your friends and alts to also 'use' it. You will notice your stamina decreasing - if it's not decreasing, step away (and have a drink if necessary) and try again.
One not-strong-enough person will still be able to make the ram work, you'll see the animation, but no matter how long you keep going, nothing happens to the palisade.
You will need at least 36 strength to damage it with a battering ram solo. Two characters with 10 strength each is enough to do damage with a battering ram. From recent experience, it is a damn sight quicker when when someone with a higher amount of strength is available, or when 3/4 feeble people are available instead of just 2.
Is there anything in that which you don't understand or can't get to work?