I'm still needing help with this :/ Can I connect them with the telephone ports. I google many search strings, all coming back un-related.
You probably could, but its going to be 56k man. Far too slow for any webserver use.
Going with what FuryRosewood has said, what are the specs of your computers? If they're 128mb pentium II or something, even stringing them together into a cluster wouldn't work - they're just too slow for any real good in today's day and age.
You might be able to craigslist them, and save up for a single nice server. You're going to need an insane amount of memory (and depending on what you're storing) HDD space, Fast nics and a few other things that these computers most likely don't have.
For comparison I ran an old socket 7 amd something as a server for about a day, even with 256 ram and tinylinux it just wasn't fast enough to even bring up a webpage for more than 10 people at a time.
Plus you've not mentioned what your cable/dsl provider gives you. Unless its t1 or better upload, then things will be too slow to even bother with. Most cable companies block port 80 anyway, so there goes http space.
I really hate to be such a downer. But running a server is no small feat. You've done right by playing with apache (the best!) and you've done right by coming here to ask questions. But cluster work is better suited for beowulf, folding, bitcoins, data processing, parallel databases, etc.
You can get a cloud cluster as a webserver from amazon, rackspace, etc, probably cheaper than the cost of electricity your 4 computers would be pulling anyway.