Top advice from MarcP.
On a practical level outlining is about breaking it down so you can build it up.
You need to know the essence of your story first off - to the point where you can write it down in three or four short paragraphs (longer for a film, but this is for a 30min comedy).
For examples go to theexcellent 'TV' resource on this site and the episode guides to some of the classics.
The episode synopsis are what you're looking for.
You need to write that down - doesn't matter what you call it - synopsis, story whatever, just write it down.
Essentially it should be the answer to the question "What happens?" (whereas a 'log-line' is the answer to the question "what's it about?")
Some would now divide that into three acts - which all stories are essentially.
1.Chase man up tree 2. Throw rocks at him.3. Watch as he tries to get down.
I don't bother - in my opinion good storytellers instinctively write in three acts.
I use a sequence approach.
Divide the story into sequences ie the bit where Del Boy has the idea, the bit where he convinces someone to do something, the bit where Rodney... etc etc.
These are like separate bits of drama that get played out to some sort of conclusion.
Now write down what happens in each of those sequences - not the jokes - but what happens.
Now subdivide the Sequence into Scenes - again not jokes, but what happens, where it happens, who's in it etc
As you're doing this (and the sequence bit) you're bound to come up with some funnies -make a note of these but don't write them into your summaries - keep them purely about story telling.
Now and only now do you start to build the script back up.
Nothings set in stone - in fact it shouldn't be - but you have a clear path, each job is a manageable one and you shouldn't get lost or overwhelmed
Keeping track of all this information can be hard.
The classic 'Hollywood'' way was to use index cards on a cork board, and there are plenty of cork board programmes out there.
I use a programme called Scrivener which pretty well allows you to work anyway you want - including index cards.
It's much cheaper than most screenwriting programmes and it'll let you do everything from brainstorming an idea to producing a properly formatted script.
Hope this helps a little.
NB You might note that in the example I've shown, I have in fact used 3 Acts - these were put on at a later date, as a lot of prod co's etc do like to see a Three Act Structure.
I just don't use it the early stages of my work.