I really like posting links, so in addition to the above suggestions, might I point you to lwpcook, especially the section about POSTs? Doesn't hurt to have the docs to study as well as live examples. :)

As pointed out, LWP is your friend - it is one of my most used modules, since it is both powerful and easy to use.

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You have moved into a dark place.
It is pitch black. You are likely to be eaten by a grue.